Well, just asking a question here, what is wrong with that? If you want to invite some like minded folks to comment on something...I don't see the harm in it.
I personally like that they created the 2nd Amendment Forum since it limits the amount of "Someone got killed by a gun in country X so we don't suck so badly" excuse threads. I say have more opportunities for folks to self-segregate.
I tend to look at things through the lens of intent. For every action, there is intent. Always.
Most of those invite only threads really only served to provide a platform to spew statist/authoritarian propaganda without any real opportunity for any meaningful semblance of challenge to the (or to provide meaningful, relevant) terms of controversy. It defeats the very concept of functional debate.
And the reality is that people knew that and took advantage of it.
I think someone had mentioned human nature previously in the thread.
Think about the USMB platform itslelf. There really is no established goal or mission statement. The reality is that it's always gonna just be a bunch of arguing because that's the only real incentive that most folks have in coming here. That said, why encourage the means to do so unchallenged? It's just bad judgment.
That's my thought on the invite only thing anyway.
Now. I get OP's sentiment with regard to this other thing he's talking about. I really do. I'm a big fan of meaningful, functional dialogue. But I'm sorry, I simply do not trust the judgment (or intent...especially intent) of some of the mods and in no way is it wise to empower them to decide what is worthy topical discussion and what is not. Again, they're just volunteers out of the same pool as everyone else. Why do political activists/commentators volunteer to moderate dialogue? What's to be had by it? Think about that. And, again, what makes their judgment any more competent than anyone elses? What's the motivation to volunteer, aside from wanting some kind of control over the direction of the board? I can't think of any. They don't get paid.
And I don't even really like referencing them in a collective way, honestly, because that's not really fair, but a couple of bad ones just naturally stink the whole thing up, observably. And how do you get the bad ones? Well...bad judgment on the part of those who decide. Or...depending on the parties involved...intent....
But...somebody's gotta say it. Otherwise it will never get said. And silence on the matter is almost always interpreted as approval or acceptance. Which only leads to more of it.
Anyway. I'll say this and I'll shut up about it. If this country itself ever does go down the path to rank choice voting, make no mistake, the omnipotent majority will absolutely insure that a principled statesman will never again have his or her name on a ballot, because the omnipotent majority is fully aware that the principled statesman will always challenge the omnipotent majority's judgment in a decision making setting, and ultimately challenge whatever program they're trying to run for their own benefit/agenda. And they donlt want that. Huh uh. You're gonna get the slimiest of the slime every single time until eventually that's all you have left. There's no doubt about it. It's the nature of things.
That may seem like I'm veering off-topic with that last thought there, but really I'm not. Not really. Just have to think things through a lot better before just jumping into things impulsively. That's lacking in society as a whole, unfortunately. It's a process of continuing growth...or decline, depending on the nature and intent of who is charged with making the decisions.