Everything announced by a company on their website, every feature list, every display video, every write up by the press, every review, is promotional activity. Anyone that is pissed at this particular instance because it's disguised as "normal" when it's actually dirty "marketing" should have a good hard think about how they believe the incentives behind information sharing work.

No, it isn't. The HN post is about CI being more affordable thanks to DO. And with Gitlab.com, it's free, can't get much affordable than that.

Many posts which land on Hacker News are for self-promotion purposes. That doesn't mean they lack good content.