The point of going all in on the gimmick is to reduce the number of non-trivial threats to as near zero as possible. Every marginal increase to the vulnerability you're exploiting actually has exponential gains, because you're basically working with a geometric distribution representing a mean time to happen of "we actually need to try for this encounter".
For example, a regular basic rogue with reliable talent at level 11 can never get lower than a 23 on a hide check. That alone means that they only have to exert effort when:
An enemy has a PP above 23
There is no source of heavy obscuration
The enemy has an action economy advantage that allows them to both make a perception check and take useful action, and a reason they need to be killed and not just bypassed
The enemy has good AoE and a reason they need to be killed and not just bypassed
That's a very small proportion of encounters already. Let's call it 5%
If you just add pass without trace, suddenly the PP to beat becomes 33. Let's call that now 4% of encounters.
That may seem like a small difference on the surface, but it has huge implications. You're going from "We can expect to complete 12 encounters trivially" and "we can expect to complete 17 encounters trivially."
Now say that having invisibility takes it down to 3%. That's 23 trivial encounters. Now say that mage hand ledgerdemain takes it down to 2.5% (Because one out of 200 encounters is about retrieving an attended object from someone with AOE damage or powerful action economy), it's now 27 encounters. Etc etc.
And those % are probably too high. Unfortunately I can't seem to find a way to search monsters by passive perception or other relevant attributes, but I think a fair estimate for the optimized stealth party is that they probably coast through 99.95% of encounters by level 11. There are several CR 20+ monsters that are a trivial challenge to them. There's quickly increasing marginal returns to extreme numbers just in terms of how rare it is for an enemy to exceed them.
The kiting thing is more complicated because your real enemy becomes geometry. But again, it's all about the increasing returns to extreme cheese. If, at level 4, you all can go back and forth 25ft a turn, shoot from 600ft away, and push the target 10ft back per hit, you're already trivializing a huge number of encounters. Getting more features to make it even more extreme has huge returns.
Right, but when calculating these values you need to consider every order of adding the characters.Far as being able to get someone back on their feet, yeah, it's a nice ability but generally you don't need everyone in the party to have it. Going from 3 to 4 Healing Worders is already a bit redundant in basically all circumstances. I'd say 2 is necessary and 3 is ideal but 4...doesn't really matter.
In a Paladin / Wizard / Druid / Bard party, for the paladin you'd add up:
The change in value for him vs nobody
The change in value for every other class solo vs that class + the paladin (a HUGE change with the wizard)
The change in value for any two of the other classes vs that pair plus the paladin
The change in value for all three of the others together plus the paladin.
To put it another way, the paladin, bard, and cleric are all equally the first, second, and third characters with healing.
But I think this is the wrong way of looking at things.For the party I suggested, Wizard/Cleric/Druid/Bard actually does get 3 Healing Worders (and I think Wizard in such a case adds much more than anything else could to the party) in addition to the maximal range of out-of-combat ability to maximise the ability to solve non-combat encounters regardless of the type of encounter. I honestly have a hard time seeing which character would be better off as a Paladin. I don't really see what a Paladin in this context would provide that a Bard/Druid/Cleric wouldn't do better aside from some potential burst (but all of those classes have other forms of nova). This is not to say that Pally would be bad again, but I do feel full casters generally provide you with more in the grand scheme of things (more ways to ensure death rolls never happen/more ways to ensure enemy doesn't get away/more ways to ensure you can solve any enemy or encounter with a single efficient effect).
If you want to decide the whole party at once, I think we can agree that the top choices are going to be specific janky exploit build.
If you want to look at the overall power level, that's nice but kind of irrelevant (being more powerful rarely lets you win more).
If you want to asses classes by their contribution to a fair party playing normal DnD, that's where I think wizards fall behind in the "Party Member" rankings compared to the "Class Power" rankings.