Right now I'm messaging 2 different groups and about 5 different people, while organising an event that's happening in a few weeks, and organising supplies and camping for a festival on the weekend. After this festival in the weekend, I can post the photos I took on Facebook, where everyone can tag each other in the photos, so they can be easily found.
For me it's an integrated social and event management platform. It works incredibly well for this purpose. If I need to find a generator for an event, I can ask in a group chat, or even put up a timeline post asking for one, and it will probably manifest. I had a friend who's laptop died and he needed a temporary replacement, so he put up a post and later that afternoon was in front of a new laptop.
There are some really shitty features that I hate about Facebook though, to the point that they induce anxiety. For messenger, being able to see when people were last active and when messages have been seen really makes my anxiety build up. I know that people aren't ignoring me and just take time to reply, because I do exactly the same myself, but it still plays in the back of my mind.
The second really shitty feature is that the people you interact with more are the people you keep seeing on your newsfeed or at the top of your messenger. I had a bit of conflict with a friend a while back, so we were giving each other some space to cool down. I kept seeing all her posts at the top of my newsfeed, and she kept appearing on the top of my contacts list for messenger, Facebook would even give me notifications that "Alice and 89 others have responded to events near you tomorrow". It actually did my fucking head in to the point where it was causing significant problems with my mental wellbeing.
I understand exactly why Facebook does this, to increase activity and engagement. But fuck it pisses me off.