Hacker News' policy is that some self-promotion <i>is</i> allowed, but it can't be the focus of most of your posts. There are people who occasionally post their own articles and such but if the majority of their posts are interesting <i>other</i> things, nobody complains (much).<p>On the other hand, I've flagged items lately that were posted three times in a day by a new user who apparently hadn't read the submission guidelines. That just looks like spam, even if they're "on-topic" for the HN crowd.
Self-promo (whether on HN, Reddit, Lobsters) or any social platform seems like the most randomly enforced thing. Popular people can self-promo all the time and never get penalized for it, even when it's super blatant. Other, lesser known people try to share 1 link and get banned, but sometimes they don't. /shrug<p>I know this seems like complaining that the world is unfair, and it is, but it should be called out more often.