The US has decentralized speech on paper. Anybody can make a website, but then Google won't surface obscure blogs no matter how relevant they are. Anybody can make an account on a centralized social media platform, but that isn't the same as being seen, which depends on the whims of whoever owns it or the politicians threatening them.

Meanwhile the centralized platforms then have the incentive to maximize engagement and the power to structure things that way. And that's how you get Trump, because polarization drives engagement.