Flaw in this argument: the bolded. Even when people are acting in good faith (which itself is somewhat less common than you seem to want to admit) binary either-or questions come up all the time.
Not in my experience.
And there's no such thing as compromise on a binary either-or (or yes-no) question. This is why in real life we have votes and referenda and so forth; to arrive at an aggregate majority answer that is still not a compromise.
Except that all those things, votes and referenda and so on, almost always involve debate and discussion and formalization. The vote simply sets the agenda; you still have to figure out
how it's done. Further, I challenge you to name anything that really is so totally, completely binary that there's literally zero possibility of exploring around it.
Because that's my experience. A hell of a lot of things that SEEM like sharp binaries actually aren't,
if you're willing to dig in and figure out what really matters.
In-game example: determined to play a Paladin, a player tries to bring one into a party. The rest of the party, in character, are each either willing to accept the Paladin or they are not. No compromise there; so the DM grabs some popcorn.....
Wait, so now you're
encouraging this stuff? I can't possibly be the only person who hears this and has a pretty skeptical reaction.
But let me give you an example of what I meant above when I said that things that
seem to be a problem might not be. First: none of the players are actually kicking up a fuss. They want to
roleplay through how the characters respond. That's not actually forcing anyone to move away from their choice of character, so....it's not actually a binary? Or at least not one that impedes anything? The expectation is that there will be an evolving story, which is exactly what I want to see anyway. You've presented a "dichotomy" where both of the results are already interesting (even though I don't really like the implications of one side, namely, the extreme risk of bad feelings developing between
players because of bad feelings or even bad actions between
characters.)
Secondly, but also more importantly, this is a perfect opportunity to dig down, even if we transform this into a true "no we don't want you to
play that" issue between players, not an in-story interaction between characters. E.g., what if you have persons A-D already in the game, and person E joins and says they want to play a Paladin.
A: "Oh God. No, can you please not play a Paladin? I just think that would be a really bad idea."
B: "Yeah, I'm with A. Sorry E, I don't think a Paladin is a good fit for this group."
E: "Can I ask why? I know the class has a bad rep."
C: "Well, if I'm being honest, three of us are Chaotic and only two of us are Good."
A: "Yeah. It's not that I don't trust you, I just...y'know..."
D: "You've had one too many jerkass hypocrite moral policemen holier-than-thou extremists?"
B: "Well I mean I wouldn't put it like THAT, but...you aren't
wrong..."
E: "I understand why you'd feel that way. That said, I really want to play a holy character, we've already got a Cleric
and a Druid, and we could really use somebody with heavy armor at the front."
C: "That
is true..."
A: "Sure, but couldn't you just play a Fighter?"
E: "I mean, you're playing a Warlock, A. Would you find a War Cleric as fun as your character, or would B settle for the Beast Barbarian instead of Moon Druid?"
B: "Okay, we see your point, but that still doesn't fix the problem here."
E: "I know. You don't want to deal with someone being a jerk, which I totally get. Hmmm.... Hey, DM?"
DM: "Yeah?"
E: "Would you let me
change classes later on? Like if I started off as a Fighter and then 'became' a Paladin, would you let me swap all my levels to that?"
DM: "Hmm. Your background and stats can't change, though any ASIs you get will of course be lost, since Fighters get more of those than Paladins do. Would that work for you?"
E: "Mm. Had kinda hoped I could change my base stats too, but I can work with that."
A: "Oh, I see. Going for kind of a Cecil-type thing?"
B: "Huh? 'Cecil'?"
A: "Character from a Final Fantasy game. Starts as a Dark Knight. Changes to Paladin later, mellows out a lot."
E: "Yeah. Would that work for you guys? Someone who
finds his faith or oath or whatever later on? That way he can be a friend first. You won't have to just trust me that I won't be stupid about stuff. We'll build up that connection first,
then I can do Paladin stuff, with you guys as trusted friends."
B: "Sounds alright to me."
A: "Okay, I guess I can work with that. I'm not gonna lie and say I'm crazy excited, but that sounds like it really could work. And I do like Cecil as a character idea. Just...keep what D said in mind."
C: "Seems a good compromise to me as well, as long as the change to Paladin is handled properly."
D: "No complaints here."
E: "Cool. And who knows? Maybe my character won't even want to switch when the time comes!"
DM: "Alright, sounds good. Send me your character sheet when it's ready, E."
This is an alleged "binary", yet when you drill down and find out the actual
reason behind the opposition, a path forward appears. Because the two allegedly-incompatible sides aren't actually incompatible. When parsed at the end result only--"I want to play a Paladin"/"I don't want to play alongisde a Paladin"--then it seems insoluble. But when you dig deeper, it's "I want to play a holy character in heavy armor" vs "I don't want to deal with a jerkass moral policeman."
Those two things aren't incompatible anymore. I've tried to address a range of responses and opinions here: A is the one who has really strong opposition, but B is also mildly opposed and C can see how problems could arise. D is on the fence, thinking A has a point but is maybe going too far. DM has no preference either way, other than group cohesion. E offers a genuine sacrifice (not playing a Paladin for the first X levels, even though that's what they'd prefer to play) in order to lay groundwork to prevent a problem from arising.
I find that
nearly all--sure, not absolutely 100% all, but pretty damn close--such alleged "dichotomies" almost always become quite soluble once you peel back the obfuscating layers and drill down to the thing people really, actually
care about. Now, obviously, I constructed this canned example and went with just one theoretically-possible path. There are many, many others I could come up with. E.g. "Okay, how about we work out the tenets of my oath, so you can feel confident they won't be harmful to the game?" or "Hey DM, can I seek out X and Y magic items, since that would let a Cleric do pretty much all the Paladin things I'd want to do?" or "Hey DM, would you let me play a Celestial Blade Warlock that can use heavy armor?" or "Could we rework the Eldritch Knight subclass to be divine-flavored?" or, or, or...
All it takes is a sincere commitment to good-faith participation, a bit of patience to try to find the underlying issues, and a bit of flexibility--for
both sides, not just the person wanting a thing or the person not wanting that thing to happen.