Well, as an example, I believe it was AlViking who bad-mouthed any player who comes to Session Zero with a character concept they're already intending to play. So...yeah, Session Zero is already too late. A player having personal tastes and interests of their own is irrelevant and Session Zero cannot help because Session Zero has the GM already bringing all the concepts of a world, but the player is forbidden to bring even the tiniest concept of a character.
And that, I think, most cleanly and neatly summarizes the problem I have with the "GM wins" argument. It pretends that it's perfectly fine for the GM to bring the world's most stringent requirements solely and exclusively because they wanted them, but the player cannot even begin to think about their own interests until they've already accepted 100% of the GM's interests first--no matter what. No discussion. No reconciliation. No attempt at consensus-building. Accept or get OUT.
First, if you're coming to Session 0 with a character concept and you don't know if there are restrictions, then you should be willing to change that concept partially or completely. You're jumping the gun, which a lot of players do because they are excited to play, but you should be aware(because the PHB tells you) that sometimes there are restrictions and something you picked might not be available or will be different from the default game.
Second, nobody is saying you cannot even think about their own interests until they already accept the DM's 100%. I often am thinking of several different ideas before a Session 0. Some of those ideas fit, and others don't. I go with ones that do, because why would I intentionally disrupt the game?
Third, as a player if you haven't heard what the campaign is going to be about before Session 0, you pretty much have to realize that it will be announced at Session 0, so you are well aware that trying to finalize a character before you know what the campaign is going to be about can cause conflict with the campaign premise and will likely need to change.
Fourth, even if you do have a full concept in advance of knowing that it will work, often there can be a compromise which will be close to what you were trying to do AND which will fit within the framework of the campaign setting, so it's still not "but the player cannot even begin to think about their own interests until they've already accepted 100% of the GM's interests first--no matter what. No discussion. No reconciliation. No attempt at consensus-building. Accept or
get OUT."
Except that the moment Session Zero begins, the player is expected to already be on board with 100% of everything simply because they accepted the pitch. That's a massive disconnect--and it really, really is the GM not getting the player buy-in. But the players are embarked; they already agreed, so now the GM has "absolute power" over them within the game, right?
Depends on what the pitch was. If the pitch was, "Hey, I'm going to be running a Middle Earth like game, so no races that aren't part of Tolkien, are you interested in playing?" and you agree to play, if you show up with a Tortle character you are basically acting like a jerk. You've agreed to play Middle Earth races and trying to get a compromise into being allowed to play a turtle man is intentionally trying to disrupt a game where you already agreed you wouldn't do that. It doesn't just make you(general you) a jerk, but also a liar and someone who is very likely to be a major disruption to the game. At that point the DM should probably just not allow you at the table and save everyone who is going to play a lot of grief.
However, if the pitch was, "Hey, I'm going to be running a political game set in Greyhawk, do you want to play?" and you agree, nothing was said about the races involved so you wouldn't at all be a jerk for showing up with a tortle to play. When you get to Session 0 with that idea, let's say the DM tells you that government involved is a bit xenophobic of races that don't look human and if you play a tortle who looks like a bipedal turtle, it will be very rough going for you and you won't get nearly the enjoyment out of the game that the other players do. Perhaps a compromise where you look human, but have tortle abilities is the best way to go. You don't look like a walking turtle, but you do get the rest, and you won't set off the xenophobic bells of the NPCs and limit your enjoyment of the campaign.
