You know what, I wasn't even right - for some reason I mixed up in my memory the following bit of the guidelines as being to not call our individual comments for being low quality, and only on seeing your reply did it click:

> "Please don't post comments saying that HN is turning into Reddit. It's a semi-noob illusion, as old as the hills."

(Though even if not specifically against the guidelines, "go back to Reddit" type comments do often fall foul of not being polite/helpful, when they'd do better to explain why another comment isn't suitable for HN than to just dismiss/insult it.)