Indeed, and if a character roleplays itself right out of the party then so be it...that character is still out there for its player to bring in at some other time and-or to some other party, or play solo, or build another party around; and the player can always roll up a replacement for here and now. (I've always held that having extra PCs "out there" tends to make for a deeper and richer campaign/setting in the long run)
And yes, sometimes in-party disagreements escalate to the point where weapons get drawn, spells get cast, and some characters end up either tossed out, charmed, or dead (or, in one memorable and hilarious - you had to be there - case, given away into slavery). The key thing is that what happens in character stays in character: if the players are laughing as these things happen, all is good.
I'd rather see these things resolved that way than by the more passive-aggressive approach I've also seen, where an annoying character is by tacit agreement among the other characters/players hung out to dry in some combat or other and left to die.
Indeed, why would they do that? Best answer IMO is maybe they wouldn't; and end up going their separate ways (or, more commonly IME, splitting into two groups that do get along internally - which means I then run two parties once each group fills out its lineup with new recruits).