I think it’s pretty normal for this to happen on launch and show HN posts (just like it’s normal for a fellow HN user to tell you that your startup can be cloned in a day.) We’re an odd bunch. :)
We don't usually let people change the subject to their own thing in someone else's launch thread. It's boorish.
We're a little less active about it in YC launch threads, though, because of the first principle of HN moderation: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu.... That's why I haven't said anything in the places this has happened in today's thread.
Fair enough. Though I don’t agree that discussing or mentioning a competitor is changing the subject, especially when that competitor addresses some of the issues originally mentioned.