>we used to all have the same 20 TV shows but now with internet microgenres we don't have enough shared culture anymore.

It has its ups and downs. It does mean that it's harder to mesh with any given stranger out there (unless you watch Sports, pretty much the last bastion of cable monoculture). But it also means anyone who does mesh with you probably is very easy to form a strong bond with.

But if you never find that person, the world can feel depressingly small. Hence the retreat to online communities and all its benfits and downsides.