D&D General Replacing 1d20 with 3d6 is nearly pointless

[Garthanos]

The fact that the increments are constant (ie a +5% step per bonus) doesn't seem that significant to me, compared to this significant difference in the actual impact it has on my chance of success.

Yes the 5% looking like it would be consistent in impact is illusionary.

 

[FormerlyHemlock]

That's a strange way to describe it. Looking at it that way, if your odds change from 0.001% to 0.01% you could say that the chance of success increased by 1000%. Yet both probabilities are too small to even be measured with a d20. Mathematically, what you're describing is basically irrelevant to meaningful calculations like weighted averages. And you haven't demonstrated how the 3d6 method makes anything better.

I won't say your math is wrong, I just have no idea how it is meaningful.

It's meaningful if the game system allows you to interact with potential bonuses and penalties. Let's take Sharpshooter/GWM for example. What's a fair penalty to give someone in exchange for roughly doubling their damage on a hit, e.g. by shooting someone in the neck instead of the torso? How about a penalty that for a normal person cuts their chances of hitting by MORE than 50%, so that you need to be fairly expert to take advantage? The raw % is less important here than whether it halves or quarters your chances of hitting.

Dungeon Fantasy RPG and GURPS take enormous advantage of optional situational modifiers like this, whether it's about targeting vitals or choosing what ground to fight on (e.g. +1 or +2 bonus to your defense for being on high ground is tactically significant) or what equipment to carry, what range to fight at, etc. What I got out of the OP is that merely flipping D&D 5E to run on 3d6 will not give you that much benefit because 5E hasn't done the necessary work to make manipulating penalties and bonuses interesting. E.g. you'll never spend any mental effort trying to determine whether you should drop your Blur spell in order to maximize your chance of successfully Disintegrating a vampire, or if it's more advantageous in the long run to keep your Blur up and just live with a 25% higher chance that the spell is wasted. 5E simply doesn't give you the option.

Information that doesn't affect any decisions is wasted, so having nicely-scaling difficulty modifiers doesn't matter as much in 5E. Actually SS/GWM is the only example I can think of where the size of a penalty does matter; there are also a few corner cases like archery duels involving monks or high-AC PCs where choosing to impose disadvantage on everybody is an interesting option. But for the most part 5E isn't a game of manipulating probability.

 

[FormerlyHemlock]

If FomerlyHemlock is who I think they are,

I mean, probably? If you think I'm Hemlock from Usenet rec.games.frp.dnd ca. 1998, or Hemlock from Enworld ca. 2014-2017ish, or MaxWilson from GITP ca. 2014-2020, then you're correct. If you think something else then maybe you're correct but probably not.

I'm definitely not Sea Wasp or Michael Scott Brown or Terry Austin

 

[pemerton]

Michael Scott Brown

I remember arguing him with him in 2000, in the lead-up to the 3E release.

 

[pemerton]

Mathematically, what you're describing is basically irrelevant to meaningful calculations like weighted averages.

No it's not.

If my chance to hit is 1/20, and then goes up to 2/20 because of a +1 bonus, my weighted average has doubled! In the context of D&D play, this would (for instance) halve my expected rounds to win a combat.