Reddit has all three (no need for email even), they might not be perfect but I can't remember any time I saw "viagra links" or other obvious spam. They have problems with accounts obviously, but you can't frame it as a spam problem.
That does nothing to speak of “auto moderator”, fragmented rules/guidelines and ilk and the sheer effort involved by volunteers.
Even then: the spam gets through. But I agree that PII is not solving this.
Where? I've seens a couple of ghost subreddits with spam, but then you see the same with ghost fb groups, weird twitter profiles, youtube, etc On even moderately sized subs I've seen any that wasn't removed quickly by the mods.
People can say mods are too expensive for fb and twitter, but there is the dishonesty, instead of paying mods they pass on that cost to us with our pii while pretending it's free.
How does allowing people to read (but not post) without logging in produce "spam"?
- Combat spam.
- Be large.
- Allow (pseudo-)anonymous accounts.
A social network can only pick two.