They don't even produce complete search results. Go to a group with a long history, and use "search this group" for a keyword that will return over, say, 100 results--some of them a couple of years old.

You won't see many of the older posts, and facebook gives no indication that they have been pruned. It's very hard to find old things without just scrolling through chronologically, which is slow and error prone.

Drives me insane.