I agree to almost everything he said and I am also avoiding all the social media. It's surprising that he didn't use his blog to share, instead a social media. He has intentionally not mentioned Twitter. Was/ Is he an investor in Twitter?
POSSE (Post on Own Site, Syndicate Elsewhere) is a thing. I don't think you can turn off replies on Twitter at least, though, so you'd still potentially end up with fragmented conversation, although you could just choose not to care about the Twitter side of it.
Yes, he is/was an investor in Twitter (according to his AngelList profile).
Although, I find Twitter the simplest social media platform to control the information stream that you consume. Actually, because of that, it is the only social media site that I usually visit.