The only thing Facebook did, in my experience, was make the web anti-social. I distinctly recall when my group of friends had stopped calling around each week to figure out what we were going to do on the weekend. I was calling people to find out what they were up to... and I got that condescending call to action, just get on Facebook.
So I did. I tried it for about a year or two. And it didn't make the web any better or more social for me. It would recommend events to attend and I'd go... but people would just be in their cliques not talking to anyone outside of their groups. Even learning about upcoming concerts and events required a Facebook account. People stopped calling and hanging out. It was all very passive: like, like, comment, meme, har, har.
So I closed down my Facebook account and haven't used it since 2009 or so. The "social web" has only become more anti-social.
Most of these web services made quite a lot of interesting innovations and such but I can't help but wonder what the web would've been like if we'd stayed true to its roots and improved the protocols and infrastructure instead of centralizing everything behind walled gardens.