I don't think that people who feel this way are necessarily expecting that you should rally to their cause. A good first step is extending a sympathetic ear. I also think that some of your questioning can also be antithetical to your previously stated goals of understanding others and achieving a fruitful discussion, as it can be off-putting and put these people on the defensive, that their cause has to be justified and rationalized in full before you can even extend sympathy or consideration in part.
I'm not going to pretend to sympathize, though. I want to actually sympathize, but I need to understand otherwise I'm just patting people on the back saying "there, there. Maybe one day WoTC will do what you want."
And I'm trying to give those who want to explain in full a platform. It's easy to say what you want, but being questioned allows you to explain how and why you want what you want.
This is clearly saying: you cannot achieve perfect balance, and individual groups are likely to deviate in one way or another, so it's not worth pursuing. The whole point of my original statement was to reject this strawman argument against perfect absolute balance.
I'm looking towards a theoretical future where perfection is possible and the results still doesn't seem very profitable. So if the best-case still doesn't seem great, then the realistic model would at least be subpar as well. Again, in terms of profit/making it worthwhile.
Irrelevant. FIghter is presented as a peer of Wizard. If they are not peers, don't present them as such. And if they are peers, make them such. Peers do not have to be absolutely perfectly equal. But they should be, y'know, peers. The player is choosing between options presented as equally valid: not "absolutely perfectly equal in every possible way such that it isn't even in principle possible to choose between them except by personal preference," but equal in the sense that anything one "gives up" is compensated for by something it "gets" in return. The way the game is currently designed, that is simply not true of the Fighter. It does not get ridiculous superlative mastery of combat; it is at absolute best, under ideal conditions, only very slightly better at combat than a Paladin or even a Wizard, yet both of the latter gain a LOT of non-combat resources.
From my perspective, what the fighter gains is less. And that less is more for some people. I've mentioned before, but some people don't want to engage with any more of the rules and story than they must. Personally, I've had players upset that whenever they're in a situation,
they are the ones who have to use their utility options because they're expected to.
Theoretically, you could not engage with something out-of-combat if you don't want to. Realistically, if the fighter has the power to break mountains, then when the party faces a mountain, the fighter would be expected to break it on behalf of the party. It happens all the time. The rogue with expertise in lockpicking is volunteered to pick locks, even if the lock might be booby-trapped and the rogue loses HP. The bard is expected to cast a charm on a person even if they might fail and cause the situation to go hostile. While you could say it's a party being bad, most would say it's common sense since those players are optimized to succeed.
A fighter doesn't have to worry about being asked to do much at their own risk or detriment. Nor are they expected to. They get to enjoy the game with less interactability and less expectations. I don't see this as a bad thing.
My question: why should I?
Which, perhaps humorously, goes back to my earlier question (that was ignored): Why is it we get Fighters who (allegedly) are absolute beasts in combat but get diddly-squat outside it (other than features everyone gets), but we never get a spellcaster that cannot even in principle contribute to combat (other than features everyone gets)?
Because combat is generally the longest and deadliest parts of D&D. If a character is bad at combat, they likely are going to die and they won't be a character anymore. Combat is also generally one of the most fun aspects for, from my experience, most players. Social and exploration are a more niche category of the game and players use those to get to the next fight quite often. It's important to know "social" and "exploration" is distinct from narrative.