Afaik a lot of stories repeat on HN, so the "newsworthiness" criterion seems a bit arbitrary. Also, shouldn't it make a difference if it is a top level thread? I wouldn't submit a story about "socialism starving millions of people".
I know, your "new" policies have been in place for a while, but I think you really kind of destroyed Hacker News. I don't understand why you worry about curbing discussions in deeply nested threads, as they would be easy to ignore by people who don't care. I don't think you worry about SEO or anything like that, so really, what is your incentive?
Also, there are lots of "boring" and repetitive threads on HN (like on global warming), I think you may actually single out "capitalism vs socialism" for ideological reasons. I don't believe you that nobody is curious about capitalism vs socialism anymore. On the contrary, the "battle" is more relevant than ever, with socialist having a real shot at the US elections. It is a question that affects most of us a lot more than most topics would.