It's not up to you. People can visit whatever websites they want, your subjective judgements about the nature of the content on the website isn't relevant. If they have a problem with the website they are free to visit another one.
> Very many people will continue to use Facebook and Twitter for news.
That's their choice. Very many people will continue to use pornhub and there is nothing the church can do about it... yet.
Is up to me to stop it? No. Of course not. Obviously not. In fact, even if I had the power to single-handedly, unilaterally, stop Facebook from doing these things, I wouldn't. Because I don't believe that might makes right (that's my wider point, after all).
What I want is a popular, democratic movement to regulate the websites that people use, in the way that the informed population think they should be regulated.
Allowing countless to be made pawns of in the name of liberty seems foolish.
Too late. People are too easy to manipulate when you can amplify whatever you want.
Yet very many of these people will continue to use Facebook and Twitter for news, rather than changing to an alternative. So your solution to the problem fails.