It was more like the monthly job thread and HN might have legitimate reasons for discouraging analogous threads for everyone's side projects.
It is also possible that the thread's pattern of growth triggered some heuristic.
For the most part you don't need to be "afraid" of comments - an article is only penalized if it has more than 40 comments AND more comments than upvotes. Most articles have considerably more upvotes than comments, so commenting won't hurt them at all. But you might want check the upvote and comment numbers before adding a comment just in case...