I just don't agree with what seems to be the majority consensus here: that PCs should always get along, have the same goals, and always be team-first.
Those aren't all the same thing. The PCs don't have to get along or have the same goals, but keep the not getting along to roleplaying, not actions that have serious mechanical consequences, especially lasting ones. Again, unless everyone has a prior agreement that doing otherwise is ok.
Here I (surprise surprise!

) again disagree, in that I see narrative coherence as absolutely vital.
And that doesn't forbid the "puff of mist" idea; but it does force the DM to have a plausible in-game explanation ready for when someone casts Commune and asks "What became of Kallios?".
If a player is asked to leave a table because they couldn't see eye to eye with the rest of the table, or wouldn't change their behavior after being asked, and then other people keep bringing up their character, unless the DM deliberately dropped hints that there was something to explore there, that reads to me as passive aggressive.
Well, first off I'm a fairly staunch opponent of metagaming.
Being absolutely opposed to metagaming regardless of context is a fairly absurd position to take, if you ask me. If rule zero is "What the DM says goes" then rule negative one is "Thou shalt not let your commitment to roleplaying your character get in the way of other people's fun." If you can't abide some metagaming to make sure that happens, then you'd better throw out any character concepts that are going to "force" you to piss off other players.
But more to the point, the problem with banning any and all PvP comes when you realize you're also in effect banning a certain degree of realism and to a lesser degree telling people how to play their characters.
Damn straight; if those things are getting in the way of other people's fun.
Realistically, people thrown together for any length of time are going to disagree, fight, get mad at each other, and so forth - just look at almost any family in the world as an exmaple of what I mean. Banning PvP means those disputes can't realistically be played out, or - in the extreme - aren't even allowed to occur; and I just can't get behind that.
Nobody is saying you can't have arguments in character, within reason. I've spent a lot of time with groups of people --- family, friends on a road trip, etc. --- and sure, we've gotten annoyed at each other, but that doesn't mean we steal from each other or injure each other, or do anything that's causing physical or permanent harm.
It also in effect bans the prankster character trope, which is truly sad.
If your idea of a prankster is someone who causes irreversible changes to the people being pranked, then yes. Yes it does. I don't think anybody here is talking about putting shaving cream in someone's palm while they're sleeping, or putting a kick me sign on their back.
Ah, there might be a difference between us: I see the other PCs as also being part of the risk that's built into the game itself (and the many front-liners I've played who have been hit and sometimes killed by friendly-fire AoE damage would back me to the hilt!).
We're also not talking about friendly-fire AoE damage here. That's a cost-benefit calculation, and sometimes a little friendly fire is worth it in the big picture. I certainly expect that you're not going to induce friendly fire that would actually kill a fellow PC, unless not doing so stood a good chance of leading to a TPK. But that's also being party-minded, not PvP.
So if Wizzie catches me in his fireball it's OK, but it's not OK if (assuming I survive) I punch his lights out for it afterwards? Seems a bit double-standardish from here......
Depends on the situation. If you were to do that at the inn after the adventure, and Wizzie could just rest it off afterwards, then that's probably closer to the shaving cream in the palm scenario. But ultimately it depends on how Wizzie's player would take to your PC doing that to theirs.