I want to acknowledge that feedback, because it’s useful.

As a follow question: is this a solvable problem between host moderation and user self moderation?

In other words: Let’s pretend NPR hosts a Reddit-like site whose primary objective is to facilitate discussion on topics shared by NPR.

NPR doesn’t outright ban everything unless it violates some terrible things.

Could user moderation NPR Reddit also expand on this? So long as they fall under the same guidelines?

I ask this question because it seems to me that there does exist some useful moderation: there are well moderated Reddits and for the most part Wikipedia is also pretty well moderated.

Yes, there are private entities with good moderation. A public entity (in the US) with those same moderation policies would have a very hard time avoiding infringement of the first amendment.