I think you overstate the centrality of Facebook. Yes, FB feeds people a lot of nonsense int he name of commerce. But extremist people with odious political views were and are forming their own social networks without FB and have been for years (not least because quite a lot of them think Zuckerberg is part of an international Jewish conspiracy).

I'm not a big fan of FB and don't have any ownership interest in it. However I think it's largely politically neutral and that Zuckerberg is just a bit out of his depth with the manifesto as opposed to being wickedly cynical - even though most people would peg me as a radical leftist.

the phenomenon that Facebook exemplifies is a real problem, and it's why I've been arguing in general terms for the destructiveness as capitalism as the only driving force in development and the superiority of protocols to platforms, so as to preserve a truly open and inclusive internet rather than one built around the extraction of economic rents. But I regard FB as a symptom rather than a cause, and try to save my anger for the people who are actively working to strip people of their rights and liberties as opposed to those who merely profit from applying technology to the existing but often unethical way of doing business.