The problem is that friend groups in Facebook are an afterthought at best and horrifically broken at times. To the point that they're nearly useless. I've had m

The problem is that friend groups in Facebook are an afterthought at best and horrifically broken at times. To the point that they're nearly useless. I've had multiple instances of Facebook deciding to ignore my default post settings for a type of post or album, posting it wide open when it should have been restricted to a certain friend group (mobile apps are especially bad about this, IME). Things I want to share with friends of family may not be things I want coworkers seeing. I don't want to share photos of drunken antics with bar friends with my grandparents. I don't want updates about a sick relative to become office gossip. Yes, the feature sort of exists in Facebook to kind of get this functionality, but there is a massive appeal in a network that treats the idea that not all acquaintances are equal as a core concept. And because it's a central value of the network, I have a lot more faith that it should actually work than the Facebook model, which has already failed me plenty of times in the past.