I'm not a huge fan of FB, and I agree the interface and behavior is confusing and unpredictable.
However, if you're a member of a FB group, there's a feed called "Shortcuts" on the left side that lists the groups you're in. If you click "Edit" next to Shortcuts, you can change the listing for a particular group from "Automatic" to "Pin to top", which will keep that one in the visible feed. Then you can click on the group name in the Shortcuts feed, and go to that group's feed. Looking at the group's feed will usually make it easier to find something you're looking for.
You can also just type the group's name in the FB search bar at the top and then click on the group to go to its feed.
I do personally prefer the forum, but there's a lot in the FB stuff that doesn't show up here. I think some people go to FB by default because it's not only where MSTA is, but basically everybody else they know. They'd rather stick with one thing than deal with multiple paths to information, for whatever reason. If I'm going to try to be sociable (those of you who know me, know I'm not very good at it), I guess I have to deal with how other folks operate. That said, I'm still a dinosaur with no instagram or snapchat.