it’s true. The phone/tablet based communities are very active: I’m very active on Vine for example, but my Instagram is less active and less “live”. Google+ can sometimes be very active if you happen to catch people at the same time… but the change in format recently made it a little strange to use. [probably ’cause I’m used to the old format].
You can LIVE in the youtube comments section just about – that’s like a social network all its own.
tumblr is very live and active, if you don’t mind the people and working their system.
Twitter is.. .well, it’s twitter.
I’m on Myspace now to see what’s happening (it still exists) and I can hear the echos.
http://fubar.com/ is a strange/interesting site. Never sure if it’s a hookup site, a friend site, I dunno. I was hooked on it years ago when FB was pretty empty and I just looked and it’s very active.
But I think a lot of ppl online are in gaming chats. Steam is where you also find a lot of people. Also twitch.tv… hm, that’s all I got for English sites I can think of.