I've never seen interesting conversations on topics I care about on 4chan. It appeals to a certain demographic that I was never a part of, not even when I was a teenager.

So you can give it as an example of a surviving community, but to someone like me it might as well not exist.

Also note that you've just left a comment on Hacker News, one of the most moderated communities on the web.

>I've never seen interesting conversations on topics I care about on 4chan.

That, as you said, might depend on the demographic.

But you can certainly find interesting conversations on Reddit.