I don't mind helping people out, but I feel like a lot of these commercially bent posters, even the small-time ones, should have their own group. They should invest the time and money and do that and if they did, focus on it. A lot of times the constant posting is annoying.
In my Facebook group I disallow for people to share their own, in my group. Likewise I don’t share mine in others since that wouldn’t make much sense rule wise.
For a Facebook group it would be better you leave it open for members to share contents but do well to have moderators who will supervise the activities of the group and ensure its serenity.