That's a rather blithe and shallow criticism of Facebook and Twitter. I could easily complain about email because of spam, but it would totally disregard its usefulness and impact. (As for Candy Crush invites and annoying selfies, Facebook actually provides tools to deal with those problems. RTFM?)

Facebook in particular has allowed me to keep in touch with a much larger social circle. It has made it easier to meet people, establish friendships, maintain distance relationships, and keep in touch with more of my extended family. It allows me to plan events quickly and on short notice, and get quick feed back on who will be attending. It helps me learn about new events or activities that I otherwise might have missed.