> HN has no recommender system so I dont count it in.

HN front page is digitally curated. HN has an opaque post ranking algorithm.

> How are stories ranked?

> The basic algorithm divides points by a power of the time since a story was submitted. Comments in threads are ranked the same way.

> Other factors affecting rank include user flags, anti-abuse software, software which demotes overheated discussions, account or site weighting, and moderator action.

https://news.ycombinator.com/newsfaq.html

Ever noticed the YC posts that cannot be commented on?