I have to agree with you, but for one thing : although Google is indeed almost unavoidable, nobody forces anyone to go on FaceBook or Twitter.
I avoid social media like the plague, so I am not subject to any "weaponization" of my Internet experience. Plus I have decades of experience in sorting the spam from legit mails in my Inbox, and I can smell an Internet scam mail from miles away.
Facebook and Twitter are useful to me though, because now all the idiots are over there, so I get a lot less spam. Give it a while, people will tire of it.
As for the next billion users, most of them will not be English speakers, nor will they even be of Western culture. I do not think Facebook or Twitter will be able to brainwash them. On the other hand, they'll certainly have their own versions available, and will have to learn to deal with it in their own way.
Being a global platform does not mean everyone acts the same. Facebook will never have the same importance to a Chinese or an Indian than it does for an American.