A lot of Hams out there will answer that question by saying, "it's good for nothing!" It's true that there's a lot of blather and garbage that you have to go through to get to the "good stuff". But that's true with a lot of things. You have to go through a lot of rocks to find the gems, you have to pan through a lot of water and silt to find the gold, you have to dig through a lot of ...... to find the best mushrooms, and so it is with Facebook.
Several of the good groups include (but are not limited to - don't want to get any one's knickers in a knot) the Field Radio group.
This group is not exclusively made up of QRPers, even though that might be an assumption you would make. No, it's made up of Hams who like to take their gear outdoors and operate from somewhere other than their home shacks. Sadly, some of them don't have home shacks to operate from dues to HOAs an covenants and things of that nature. Reading their posts and looking at pictures of other portable set ups is enlightening and has given me a few ideas to ruminate on.
Another group more germane to QRPers is the QRP Outdoor Radio group.
This group was founded by Tim Carter W3ATB, and is a very good group. Lot's of posts are shared between this group and the Field Radio group, but this one had the distinct QRP flavor to it. Pictures of portable setups in this group always include the usual QRP suspects and there's a lot of good ideas posted about antennas, field packs, etc.
The last group I am going to mention in this post is truly an international one. It's a closed group (meaning you have to formally ask to join and be accepted) but is easy to join. It's called the KX3, FT-817, IC-703, QRP and Portabel (sic) group. In this group you will have to use the "translate this" option almost all the time, as 95% of the posts are in languages other than English. The good thing is the translator, while not perfect, allows you to get the gists of the posts, and it's nice to get a fresh take on operating portable from another point of view.
Yeah, you can outright dismiss Facebook and social media all you want. But if you're patient and take time to dig through the layers and don't mind tossing the bad while keeping the good - you're going to find a lot of very useful information.
72 de Larry W2LJ
QRP - When you care to send the very least!