I don't disagree with much of anything you've written there, but corporate dominance has been an issue for a long time and the impact of social media companies

I don't disagree with much of anything you've written there, but corporate dominance has been an issue for a long time and the impact of social media companies is trivial compared to the impact of companies that e.g. kill citizens with addictive drugs for profit, withhold life saving drugs and medical treatment for profit, hoard and reserve huge swaths of residential property for rent seeking, contaminate the water table and arable land for natural gas etc and the political proclivities of these companies is never scrutinized outside of partisan politics. I'm not saying that Facebook isn't also a problem, but it seems very much like bikeshedding to tie ourselves into knots writing new laws so that people have the right to share low-effort memes on Facebook's servers when there are so many real problems that could be solved with new laws.