I'm going to give benefit of the doubt here. Please, please, please don't make me regret this.
Okay, so some people like in our world where there's not easy peasy nice and squeazy fix to paralysis and amputation and other reasons one might be in a wheelchair... have to be in wheelchairs. It's part of who they are.
Those people, like all of us, sometimes want to play a character who is like them; to see people like them in their entertainment.
To deny them that and tell them to instead have their character use the super easy, barely an inconvenience solution to stop being how they are invalidates their experience and patronizes them for wanting to play someone like them. It is wrong-headed and rude at best and outright cruel and insulting at worst.
It's like telling me to have my character use skin bleach because there's no elves with my skin tone.
I 100% agree with you that representation matters and that players should be accommodated.
But I'm not clear how to do this well. Could there be a "magic wheelchair" that can go up stairs etc and pivot quickly in a fight (modern fencing is in a piste - a back and forth track - and that really does not mimic actual melee combat well), and duck away from fireballs so that the PC is not negatively affected? Absolutely, sure, I can get behind that. But then I run in 2 problems
1 is "veracity" - sure again, I accept the magic wheelchair. But if we are in a world where this is possible, why a wheelchair and not... I don't know, golem legs? This is the lesser of the two problems, by far, but it is there.
2: Is the magic wheelchair invalidating the experience? If the magical wheelchair deals with all the mobility problems and other issues the player has to deal with in real life... if the wheelchair has no impact on the game, then it's just... a cosmetic choice? On the other hand, if the wheelchair has issues/challenges (difficult terrain? you can't pass!) then it would become rather unpleasant to the player I imagine.
I definitely can ignore problem 1. But I think understanding how to do it
well, to solve problem 2, is key (for me at least). And it's not so much a mechanical rules problem, it's a "how to best approach it" problem.