Why would a platform have to deal with it? The only issue is escaping government regulation (censorship). And that is a different problem. I'd rather fight for freedom of speech than trying to censor my users.
Also there would be no reason to switch away from Twitter if you want to censor users anyway.
And I disagree that the spread of misinformation is such a huge issue as you make it out to be. Misinformation existed before the internet, it isn't caused by it. The internet makes it easier to double check information.
If watching a boy burn ballots makes people burn ballots, I don't think Twitter is the problem here. I think those people have some other deep seated problems. I'm sure I wouldn't burn ballots if I saw that video (I haven't).