yes, these days almost all brokers run FB page. But, the question to ask is, are the posts regulated? does the broker delete any negative comment/complaint from any member?
Does the broker force traders to compulsorily post/like their page on FB?
I've seen brokers offering miles/points to login to FB and liking their page. More points for good comments.
None the less, i'd follow my broker's FB page to keep updated of any news related to platform/competition/offers etc.
And again, sometimes, the best way to get in touch with any real person from broker's office is to use FB.