I've been in online discussion forums of one sort or another for over 20 years (yea, back then we used email..
So many groups start with a focus then become a "free for all" as time goes on and no one wants to be the hard-*** keeping the conversation on-topic (most of the Facebook RV groups are feel interchangeable for this reason).
I've also been a moderator on a Jeep-related board with thousands of members. It gets to be a pain to run a clean board.
So if a group is for "owners"...then I don't mind if it's restricted to owners.
It's free to start a FB group - so if you want one for "potential owners" then start one..
I don't like that the popular RT Facebook group doesn't allow linking to blog posts (unless you're the guy who started it). But that's OK - I just dont participate there as much because I hate retyping stuff I have already captured in a blog post. I don't feel better or worse about the RT company because of it.