Stumbleupon was kind of like that. Along with being an early type of link aggregator, any website would have its own comment section that was only visible to other stumbleupon users.
I used to enjoy it, and it looks like it may still be alive in some form. But I’m not brave enough to see how shitty it’s become. I’ll keep my rose tinted glasses on.
I think the answer to why there isn’t a modern alternative is under the History tab on that Wiki page.
Fun idea though, I had never heard of that one.
I assume it’s the same reason CS got rid of tags.
The smoke bomb clears and there’s suddenly a giant vagina or gay sex filling your screen, and you have to stand up to block the screen because you were on the family computer in the living room.
Man it was so much fun to see the clever shit people had qs tags