You'll notice, here, that I've avoided using the term "realism," simply because that word is often understood to mean "functions as per the real world." While that's sometimes what people mean, more often (in my experience) they're referring to the definition which I'm assigning to the tabletop RPG version of verismilitude: a world that operates in a manner consistent with its own internal logic.
The problem is, this is what a LOT of people
claim they are doing, but when you actually challenge them about it, it's no longer simply a matter of the world being self-consistent. If you give explanations for beyond-IRL-physics things, such as non-magical sources of "healing,"
that's not enough in a large number of cases. This implies that self-consistency is inadequate to actually capture how real people use the term "verisimilitude." Real usage of the term very frequently--not always, but frequently--smuggles in "as much similarity to my [the speaker's] understanding of the real world as possible." But "verisimilitude" + "as close as possible to what I, personally, know of the real world" is simply a fancy way of saying "realism."
This is an extremely serious problem with the whole discussion.
Playing in a tabletop RPG is playing in an imaginary world. But because the imagination is whimsical and capricious, we seek to ground that mental construct according to rules and limits, imbuing it with characteristics that are (by mutual agreement with ourselves, our fellow players, and other fans of the game/setting) held to operate in a certain way, giving the setting a sense of groundedness that makes it come across as something more stable and concrete than a flight of fancy. And the more that world's operations, characteristics, and specifics are defined, the more grounded it becomes, making it more engaging as we're better able to transport ourselves "into" that world during the course of play.
Groundedness is the actual
goal here. Verisimilitude, or realism, or whatever else, are simply tools intended to achieve groundedness. Hence why I propose that we just aim for groundedness directly, rather than constantly invoking these other things which, IMO, lead to so many
more arguments and distractions. Discussion of how to produce or develop a grounded feeling in a setting or work would be much more productive than asserting that X thing has more "verisimilitude" or Y thing is more "realistic" or whatever.
And the thing to remember is that adherents of versimilitude know that. Even if we leave aside that different people will have different preferred styles of play, want different degrees of math in the rules, and like different settings, the idea of "verisimilitude uber alles" tends to be something put up by opponents of verisimilitude (as a consideration in play) rather than by the people who actually value it. While there are always third- and fourth-hand stories about some frustrated novelist serving as a GM, most of the time this isn't going to be the case. Different strokes for different folks, and all that.
I mean, maybe I am in fact becoming exactly what you describe here, but I have had multiple people tell me point-blank that it is better to have an openly, actively dysfunctional game--a game which actively opposes player enjoyment, which impedes players from doing what the game is designed to do--if doing so ensures greater verisimilitude,
for any amount of verisimilitude gained. Concessions are made only in those cases where it is truly almost impossible to get further verisimilitude, and such cases are treated with intense regret, a wistful "if only...." Practicality, treating verisimilitude as one value which we should prefer as high as possible
without painful sacrifices elsewhere, is simply not an option.
Rather, it's that immersion takes a hit if the aforementioned internal logic of the setting is flouted
Is that...really the case? Because it seems to me that there's plenty of ways one could explain something liek that within a setting's internal logic.
It seems to me that the
actual logic broken here is one that is entirely external to the setting: "Power must be earned." Which has nothing to do with verisimilitude (I think we're all pretty keenly aware that there are a LOT of people who have done nothing at all to earn tons of power IRL...), but it absolutely does have to do with immersion--and that's part of why dragging
another vague, problematic term into the mix doesn't help. Instead, it can just be stated as an opinion about settings: "I don't find this concept well-grounded, which means I just can't accept it as a positive contribution to the game." Or, to use my more typical phrasing here, the player failed to sell you on the concept.
It's a lot simpler to just ask players to truly sell you on the concept they want to play. Sometimes, like with your "I literally just want to be The Flash" example, that's not possible. You simply aren't buying what they're trying to sell. But, in general, such things are pretty rare IME. Most of the time, the GM is at least
hoping to be sold on whatever concept the player brings, and vice-versa.
More usually, there's an expectation that whoever wants it more should be acquiesced to. We see this a lot if someone says they have a great deal of personal investment in a given idea, and that not being able to put it into play will be injurious to them. In some cases, this is presented via a referendum on the other side's moral character, in that if they don't back down they're a bad person. Because magic elf games are very serious business indeed.
Personally, I would call this a very poor (and easily exploited) boundary condition. Someone can want something deeply, but not for constructive/pro-social reasons. It is, in fact, quite likely that selfish players will try to exploit such a standard by staking their whole enjoyment on being the best/strongest/only/etc. in whatever thing, which leads to serious problems. Sort of like the adage that anyone who wants power doesn't deserve it and anyone who deserves power doesn't want it.
Instead, I see it as a relative weighting of impact. There are certain lines I'm not willing to cross, as GM, because I don't believe I can continue to provide a fulfilling, interesting game experience if they are crossed. Likewise, I as a player can't really enjoy certain genres (e.g. grimdark, I'm
so f#$king sick of grimdark) or situations (torture, abuse, the usual), and if I'm exposed to them it
will show through in my RP and demeanor. I'm just not gonna have a good time and that's gonna sour the mood.
But apart from having just a few bright lines (whether as DM or player), I do my best to be accommodating, and I expect the same from my players and GMs. It truly is almost always possible to make a concept work. I just find that a lot of GMs are shockingly inflexible and disinclined to any form of discussion or consensus-building. "My way or the highway"-ism is unfortunately all the rage today.
personally tend to find that an immersive world is fun for everyone, whereas an individual's PC tends to be fun mostly for them; hence, the PC should (more often than not) be the one to back down if the GM explains that their character isn't a good fit for this particular setting (though ideally that's a last resort, and the player's desires will be kept in mind when the next campaign is being designed).
Whereas I find this is used very often (thankfully by people who don't GM for me; my GMs have almost always been lovely people) as simply an excuse to never even bother trying to build a consensus in the first place. "You want to play a <foo>? No, hell no, and never darken my door again." And yes, I
have actually had someone use that exact phrase, in full earnest, as their response to someone asking if they can use
perfectly reasonable existing mechanics for a character they find interesting but which didn't fit into the speaker's preconstructed world.
Hence why I say things like "it's the GMs world, you just happen to witness it." Because I hear things like the above from actual people.
