Okay, I'll share a pet peeve about Facebook. It's when a post appears in my feed which I can do nothing with except share it. I can't interact with it in any other way except sending a friend request to the poster, who isn't a friend. The only reason it appears in my feed is because one of my friends interacted with it in some way.
I realize this is because the person who posted it locked down all interaction with their posts, but in that case I really don't need to see it, do I?
I consider this a bug, but clearly Facebook does not.