I'm calling out the schools this time because when I submitted a post titled "YC Winter Tour 2016" last year, this is how it performed on HN: https://news.ycombinator.com/item?id=10881402.
I can't imagine the amount of crying from the community if the hosts of the site would take special privilege to pin their posts at the top. (I'd be fine with it, as it's their house, but I think they actually are better served to only take a small privilege with the jobs and show posts and otherwise leave the site to the users to vote/curate.)