I think there's a lot of people keeping 'casual' friends, just because they're there (online). And by that I mean not like a forum where you log in and see who

I think there's a lot of people keeping 'casual' friends, just because they're there (online). And by that I mean not like a forum where you log in and see who's online or chat on topics of interest, in this case those 'friends' are there ready to communicate instantly, all topics are presented, etc. I.e. they like posts, comment and stay across events of vague acquaintances because it's easier than 'un-friending' them (and maybe some FOMO too). I.e.I.e. They're friends we'd otherwise do without, but yet put in light effort just because and it adds up to more than expected.