Having Old Friends in Facebook Without “keeping Up”

I feel like one of Facebook’s main purposes is to be able to friend request those friends from 4 or more years ago, but when a couple of them found me, I realized we just had like 3 or 4 conversations. And I started thinking that it makes it even worse to be able to communicate with someone you don’t see anymore, but not doing it. All we say is “we should hang out sometime” and “sometime” never comes.