From a cursory search, it looks like they aren't banned, but the algorithm makes them fall faster. It stinks, they are often good reads (although maybe the discussion isn't always that deep).

https://news.ycombinator.com/item?id=23117614

I hope not. These are some of my favorite posts!

AFAICT penalised in the algo but permiter:

https://news.ycombinator.com/item?id=23929687

Recentish dang commentary:

https://hn.algolia.com/?dateRange=pastYear&page=0&prefix=fal...