I go on them and try to get people to join here. Some of the advice on facebook is so bad.
There's one 15yo aussie kid that runs a facebook and a youtube advice channel.
In a recent post he said (and I quote near enough)
"I finally worked out what's wrong woth my 40 gal. I realised that you need to do water changes"

More than a few groups on Facebook have been started by people who have absolutely no clue what they're doing for no other reason than them being too lazy to even search Facebook for groups that already exist, and much prefer people join "their" group to help them. This frustrates the hell out of me because if they can't be bothered to search for FB groups, they probably won't do actual research in this hobby.
Inevitably, they wind up with a clueless admin and a whole heap of newbies joining who lack the knowledge to realise how bad the information in the group is. Ultimately, the clueless lead the clueless, and the best you can hope for is a couple of reasonably smart individuals join who take the time to do research and understand rather than just decide the only "correct" way is whatever way has "worked" for them in the 3 months they've been running a fully stocked system.
Of course, when you look at the behaviour of some of the more experienced folks on the better groups, they're not exactly newbie friendly, and it's not hard to see why they wouldn't join some of the better established groups.