I have no way of knowing who wants to see any individual pictures. My parents want to see nearly all. What about my second cousin who I haven't seen in person in 15 years because she lives so far away? What about the running back of our high school football team? I'm not close enough that I'd send any pictures to either of them, but in fact they like that once in a while they see pictures of my kids and remember I exist.
Facebook solves a real social problem that text, and phones do not solve. (There are other solutions, but Facebook is the popular one)
What made Facebook useful for me is when I blocked all games. I'm slowly eliminating political posts as well, but since I'm active in politics some of my real friends are also active which makes this impossible.