Orius
Unrepentant DM Supremacist
I'm not entirely sure what this would really bring to a D&D game specifically. A modern, sci-fi, superhero,or horror game among possible genres are different, but this topic is specifically about D&D.
For one, there will be impacts on adventure design. A bog standard dungeon crawl will be more difficult to set up for a disabled characters. How many depraved cults, insane wizards, or tyrannical warlords are really going to care if their lairs are accessible? That doesn't mean it's impossible, but it also potentially complicates the DM's work as well, since he'll have to make sure adventures don't kill off the character early, make things patronizing, run things in a way that the disability is irrelevant, or other such problems. That doesn't mean you can't play a disabled character at all, and there are examples of such characters in legend and fantasy fiction, but I think D&D is likely to handle it poorly.
Then keep in mind the world building. D&D usually depicts premodern worlds, and mundane tech levels usually don't go beyond the Renaissance. Any thing later tends to start getting gonzo, and there's a conventional wisdom that the rules don't handle it well. Such premodern worlds are unlikely to have the technological or medical advances which help disabled people cope today, and disabled individuals often had it quite difficult in the past unless they were born into the privileged classes. Any methods to mitigate such difficulties are likely to involve magic somehow, and that's another set of problems.
So you want to use magic wheelchairs, prosthetics or other such devices to overcome the problems? Well, D&D kind of messes with that in several different ways. First off, magic item acquisition is something that usually needs to be kept rare for the sake of game balance. The current rules set seems to discourage easy acquisition of items and seems to prefer low amounts of magic items.
Then there's also the matter of cleric magic. Lesser restoration in 5e cures blindness and deafness and is only level 2. There have been various spells in the past to restore things like lost limbs, and heal handles a variety of problems. Now 5e does take a step back to old school vagueness giving DMs and players plenty of wiggle room for arguments, but really heal should be able to take care of most cases, with maybe regeneration and greater restoration taking care of anything else. 5e does mess with the cleric spell list quite a bit though, and there's stuff I'm not really familiar with. But in any case, cleric magic can probably heal any sort of disability a player can think up, and overall, it's probably the biggest factor where this a D&D game would make it difficult to do this properly. The only limit is the cost of healing magic from NPCs, but in some situations it might just be easier and possibly cheaper depending on whether or not magic items can be bought for the PC to find enough treasure for a permanent cure. Or even better yet, wait for the party cleric to reach the right level to cast the spell for free. You could get around this problem by doing a low magic game,but that already makes things harder.
The rules also don't do a great job of modeling disabilities either. Old school of course had traps and the like that would break or sever limbs, and there were always blindness and deafness effects. The effects would vary quite a bit to, anything from a -1 or 2 on an ability score or a reduction all the way to 3. Or maybe penalties to hit rolls, AC, saves, automatic save failures or the like. There's inconstencies because D&D tends to be abstract about damage. Some critical hit systems over the years added the possibility of severely debilitating PCs but Gary hated them. That was probably a matter of game balance and not wanting a lucky roll to give the PCs an easy win over enemies BTW, rather than any sort of ableism, because Gary sarcastically proposed some additional crit effects in an early issue of Dragon (in response probably to Dragon 39's (in)famous crit tables) that were ludicrously lethal to PCs. And all of this are disabilities acquired through adventuring mishaps.
Usually disabilities from birth get modeled through flaws or a similar system. And I won't allow them in my game at all because flaws often being exploited by min-maxers. If they take a disability as a flaw, they usually pick something where the downsides are very easily ignored and it lets them be more powerful. Min-maxers aren't going to bother roleplaying the difficulties of being disabled, and they won't build a character with actual mechanical penalties that will matter.
Then you get the "real roleplayers" who think playing with any kind of bonus is unrestrained munchkinism, and they'll look to dump as many penalties into their scores as possible with the exception of Charisma unless they're playing a bard or something. They'll play disabilities with all the problems in place to prove their roleplaying supremacy. If they don't get insulting about it, they'll probably annoy the other players unless they're all "real roleplayers", in which case I wouldn't be playing with them.
I wouldn't force players to play a disabled character either. A player who feels stuck with a character is likely to suicide the character, act out in a passive aggressive fashion, or something else. As a DM, I don't think it's good DMing to take player agency away.
And finally, it's generally accepted that settings need rules that support the setting, you can't always tack a rule system on to a setting and expect both of them to work well together. I think this is a related case. The bottom line is that my arguments above basically sum up to D&D is a poor system for people who want to explore disabilities through roleplaying.
The tl;dr version:
D&D's mechanics handle this poorly.
Magic in a typical D&D game makes it irrelevant.
For one, there will be impacts on adventure design. A bog standard dungeon crawl will be more difficult to set up for a disabled characters. How many depraved cults, insane wizards, or tyrannical warlords are really going to care if their lairs are accessible? That doesn't mean it's impossible, but it also potentially complicates the DM's work as well, since he'll have to make sure adventures don't kill off the character early, make things patronizing, run things in a way that the disability is irrelevant, or other such problems. That doesn't mean you can't play a disabled character at all, and there are examples of such characters in legend and fantasy fiction, but I think D&D is likely to handle it poorly.
Then keep in mind the world building. D&D usually depicts premodern worlds, and mundane tech levels usually don't go beyond the Renaissance. Any thing later tends to start getting gonzo, and there's a conventional wisdom that the rules don't handle it well. Such premodern worlds are unlikely to have the technological or medical advances which help disabled people cope today, and disabled individuals often had it quite difficult in the past unless they were born into the privileged classes. Any methods to mitigate such difficulties are likely to involve magic somehow, and that's another set of problems.
So you want to use magic wheelchairs, prosthetics or other such devices to overcome the problems? Well, D&D kind of messes with that in several different ways. First off, magic item acquisition is something that usually needs to be kept rare for the sake of game balance. The current rules set seems to discourage easy acquisition of items and seems to prefer low amounts of magic items.
Then there's also the matter of cleric magic. Lesser restoration in 5e cures blindness and deafness and is only level 2. There have been various spells in the past to restore things like lost limbs, and heal handles a variety of problems. Now 5e does take a step back to old school vagueness giving DMs and players plenty of wiggle room for arguments, but really heal should be able to take care of most cases, with maybe regeneration and greater restoration taking care of anything else. 5e does mess with the cleric spell list quite a bit though, and there's stuff I'm not really familiar with. But in any case, cleric magic can probably heal any sort of disability a player can think up, and overall, it's probably the biggest factor where this a D&D game would make it difficult to do this properly. The only limit is the cost of healing magic from NPCs, but in some situations it might just be easier and possibly cheaper depending on whether or not magic items can be bought for the PC to find enough treasure for a permanent cure. Or even better yet, wait for the party cleric to reach the right level to cast the spell for free. You could get around this problem by doing a low magic game,but that already makes things harder.
The rules also don't do a great job of modeling disabilities either. Old school of course had traps and the like that would break or sever limbs, and there were always blindness and deafness effects. The effects would vary quite a bit to, anything from a -1 or 2 on an ability score or a reduction all the way to 3. Or maybe penalties to hit rolls, AC, saves, automatic save failures or the like. There's inconstencies because D&D tends to be abstract about damage. Some critical hit systems over the years added the possibility of severely debilitating PCs but Gary hated them. That was probably a matter of game balance and not wanting a lucky roll to give the PCs an easy win over enemies BTW, rather than any sort of ableism, because Gary sarcastically proposed some additional crit effects in an early issue of Dragon (in response probably to Dragon 39's (in)famous crit tables) that were ludicrously lethal to PCs. And all of this are disabilities acquired through adventuring mishaps.
Usually disabilities from birth get modeled through flaws or a similar system. And I won't allow them in my game at all because flaws often being exploited by min-maxers. If they take a disability as a flaw, they usually pick something where the downsides are very easily ignored and it lets them be more powerful. Min-maxers aren't going to bother roleplaying the difficulties of being disabled, and they won't build a character with actual mechanical penalties that will matter.
Then you get the "real roleplayers" who think playing with any kind of bonus is unrestrained munchkinism, and they'll look to dump as many penalties into their scores as possible with the exception of Charisma unless they're playing a bard or something. They'll play disabilities with all the problems in place to prove their roleplaying supremacy. If they don't get insulting about it, they'll probably annoy the other players unless they're all "real roleplayers", in which case I wouldn't be playing with them.
I wouldn't force players to play a disabled character either. A player who feels stuck with a character is likely to suicide the character, act out in a passive aggressive fashion, or something else. As a DM, I don't think it's good DMing to take player agency away.
And finally, it's generally accepted that settings need rules that support the setting, you can't always tack a rule system on to a setting and expect both of them to work well together. I think this is a related case. The bottom line is that my arguments above basically sum up to D&D is a poor system for people who want to explore disabilities through roleplaying.
The tl;dr version:
D&D's mechanics handle this poorly.
Magic in a typical D&D game makes it irrelevant.
