I agree with your diagnosis of the problem 100%. I am not sure about the solutions though. Basically you're calling for a ban (or flagging) on certain ideological positions. So we'd have to build a library of ideological positions that have been identified as propaganda, and then have people mark posts and comments as those categories as they come up. In the end it sounds like a straight-jacket kind of environment that makes free discussion difficult. I think #2, 3, 6, and 8 would devolve in to this. Similar arrangements have been attempted on many subreddits on reddit, and they typically lead to an extreme echo-chamber environment. But perhaps I am wrong.

I most like #7, I think it'd be smart for users to have a site-wide "reputation" in some way that is displayed alongside their username at all times.

I also kind of like what /r/conspiracy did, where they require a 2-sentence "submission statement" that is a comment explaining why they posted their original post.

Like you said, an ideal solution would be self-managing and wouldn't require mods or admins to constantly watch it and have to flag things. A system like that seems to lead to power-hungry mods, which leads to corruption and then eventually the site falls apart.