I think there’s gray areas where someone comes in hot to play devil’s advocate and if they have a history that looks like a normal contrarian person elsewhere they might just get a removal and/or a warning, but if they’re a 2 day old account with 5 one word comments, there’s no reason to give them the benefit of the doubt.
Granted, you shouldn’t expect mods to try to figure out your personal history and state of mind to know you weren’t trying to troll in your very first post in their community, but it’s at least something to try to sort out those gray area comments. Or something to review if the user appeals their ban.
And yeah, taking your bans with you in migration would be the cost of maintaining that history. It’s a commitment to owning your own posts and history.