I’ve found that those Facebook groups have quickly become Reddit-esq with the level of gatekeeping I’ve seen. There’s a very well know British jazz saxophonist that started a Facebook page last year and he would go from group to group bashing what he believed to be inaccuracies in peoples posts in a pretty vile way. He seemed to think that he was the keeper of knowledge regarding certain musicians and would literally trash talk people that had any different opinion to his.
And that’s all just one guy