It's maybe fine to post one comment about your competing service—maybe. (I'm not even sure about that, to be honest, but people do it.) Pushing the envelope beyond that is too much.
Btw, this applies to all startup launches, not just YC companies, and we moderate other threads exactly the same way when we see this dynamic. From my perspective it's about the kind of community we want HN to be.
Non-launch threads are different of course. I'm sure your work is very good and you're completely welcome to participate on HN.
I've detached this comment from https://news.ycombinator.com/item?id=29166416.
I'm trying to share that much of what is described in the post and discussion is currently being formalized - and there are different interpretations and technical solutions that various teams including what gallery is proposing.