Thank you for your detailed perspective.

I believe a general robust 'show me popular content' solution is TrustRank, similar to PageRank that Google successfully uses for the decades-old open ecosystem, which is Web. 

If you add your following list, then you could get 'popular content people I follow engaged with', which is kinda what Twitter does.

With regards to a genuine question being downvoted by the crowd - that seems hard, need to think on that.