At least part of what I found was that there did not seem to be much actual discussion. It didn't really even matter whether it was a video, a text article (like making food), or an event. A huge percentage of "conversations" ended up being nothing more than notification references after the first 20-50 comments. It was really rather surreal to look at. I hadn't logged on in a while.
Initially, I couldn't even tell what was going on. Comment after comment where people just stated someone's name and then someone replied with someone else's name. In most cases, once the back-and-forth name reffing started, all actual conversation died quickly.
It's technically "sharing", since they're notifying FB members of being mentioned somewhere. Yet it doesn't really go anywhere externally, and very quickly kills off all further discussion in thread.