Isn't the first alternative to "free Facebook" rather "free blog on medium/blogspot/..."? The own domain of course is optimal, but not absolutely necessary. And if you can live with a subdomain somewhere, but want it to be independent of your content hoster, those can be had for free, too.
But in terms of free speech, TOS about what you can say, acceptable use. Also there's the matter of longevity, company shuts down and all content is gone, editorial control, like here you can't edit past a few minutes, and moderator interference. Advertising becoming too invasive or distracting, popups, or price increases. Blogger does have a content export, last I checked, and WordPress will import that, which has created great opportunities for some people! Also a Medium could push you under a lot of offensive content, bury you in navigation, maybe flood the page with "related articles." Or with Facebook, the algorithm just hides you from your friends, same difference. It's a trap and it plays out over and over, most people learn the hard way. Also the older content farms find out a database with a billion blog posts is tricky to maintain, response times increase, which is why many old articles just 404.
