According to article, the whole authorization system is flawed. But we haven’t invent a new one and the one we’ve got never meant to be private, it is just a way to separate users from each other. We need something unique, a "primary key" for our DB, and that’s email or phone or username that has to be stored somewhere. A server, someone else’s computer, call it what you want. It has good privacy between users, but the admin can see everything, because otherwise management of the service would be impossible.

There is no anonymity, there is always someone you have to trust in the chain of WAN networking (DNS,ISP,VPN). If you want anonymity and privacy, you selfhost (examining the code is also a prerequisite). There is no other way to do it.