> "who develops or maintains meaningful relationships on Facebook?"

I've done both. I've also formed and maintained meaningful relationships on other websites.

There's a definite cost-benefit tradeoff. It can be a huge time sink. It can bury you in games that aren't even remotely fun. It can lead to ideological arguments that destroy friendships. But it can also help you keep up with friends and relatives, reconnect with old friends, and even discover new friends-of-friends who you'd never have the opportunity to meet in person.

It's really a matter of how you and your friends use it.