Again, your use case is not the only use case. Facebook doesn't provide value
for you, and that's perfectly reasonable. But at this point you're basically a guy who doesn't care for falafel standing outside a packed falafel restaurant trying to figure out what character flaw drives people to eat there, since
obviously they can't just like falafel.
I don't use Facebook much, in part because of how awful its policies are, but when I do use it, it remains a fantastic tool for keeping in touch with friends. At this point someone always declares that it's actually just narcissism, because email and IM exist and nobody actually needs Facebook, which is a lot like someone 20 years ago declaring that this email thing is just a fad because we already have phones and mail.