

At some point on the Web (in my childhood, in the Russian-speaking parts - around 2002-2004) anything requiring registration was treated as some sort of closed club, and that was about just registration. Though people exposed their ICQ UINs and email addresses, so that you could chat with them (that’s the old way you’d DM a person whose post you liked).
I’m not sure about all these rules of what websites should and shouldn’t do. Perhaps websites should be always treated as some untrusted alien space that can possibly do anything. If you want to do something where such a leak is really bad, or anything worse than a pocket theft of 20$ - then perhaps such a system shouldn’t rely upon untrusted centralized service having everything.
I like the social model that existed then, though. It was somewhat global, now we have modern Web services (even if in Fediverse) that expose everything over the Web, posts, DMs and so on. Back then forums were websites, DMs were in ICQ\XMPP\Skype, email as its own thing, feeds as RSS.
That. Plenty of very good games were made for PS2.