Do Facebook Readers Groups Even Work?

I'm trying to get past my intense dislike of Facebook, but anytime I go there, I'm reminded of why I hate it so much. Does anyone on the site do anything besides promote? That's not really engagement. Do people actually talk to each other? It's like subscribing to only the classified section of a newspaper, except less interesting. 

Everyone, from David Gaughran to Average Joe on Reddit says Facebook is the place to be. And, of course, Google claims that the site is tops for no-cost book promotion. So, being supremely bored, and since I "had to" check on my failing boosted post (Will it run out soon? Please?) I decided to scan the selection of readers groups.

The offerings are not promising. Also not as abundant as I was led to believe. Many remind me of my cousin's website, which she hasn't updated in about five years. (Why is she still paying for hosting?) But I've been there---you have what sounds like a good idea, but then it peters out; nobody but two people join and then they forget about the site, too, and eventually...

But back to Facebook. I looked at the groups that have a good number of members. Some are explicitly labeled, "Authors and Readers" groups, some are just for readers. As for authors' groups, I'm not interested. Why would I be? If I have anything to say, I'll say it here. I'm not a joiner at all, but if there's a potential upside, I don't necessarily mind clicking a "join" button. What's the worst that could happen? A flaming arrow will burst out of the screen and pierce my heart? (hope not.) So, I began by reading a group's rules. Frankly, for an authors and readers group, I don't get the "no promotion" rule, which most of them seem to have. I don't know what else an author would join the group for, other than to promote. 

And oddly, even with that rule in place, the posts show otherwise. Lots and lots of promotional posts, unless I don't understand the definition of promotion. 

Some groups require admin approval to join, like it's a super-exclusive club. Others seem to be run by vanity presses, since all the posts are from one specific company. I also found a group in which everyone posted in Hindi (?) I'm not sure; I know English and un poco de español; that's it. Citizens of India are heavy users of social media, especially Instagram and Facebook, so I wasn't surprised. I would have asked to join, but that group does seem exclusive.  

Then there are the little, tiny clubs; presumably groups of real life friends, although why they don't just talk to each other in person, I have no idea. 

I did also search specifically for women's fiction readers, and found one group. Its rules state firmly that it's for readers ONLY, so piss off (I guess). Guess they don't want to find new books or they're trade novel snobs.

So, you tell me. Have you joined any Facebook groups as an author? And if so, did you derive any benefit from them? 

My current opinion is that they're basically worthless.