The problem with having a site-wide rule against complaining that the site is becoming Reddit is that when it actually becomes true you're prohibited from telling the truth.
There is no site-wide prohibition - which is obvious since these comments would be prohibited.
There are guidelines and each guideline is mostly loosely encouraged by the community here by downvoting - in effect becoming community standards. However a well written exception can receive upvotes (even though strictly against guidelines) because it is a community and individual judgement mostly gets priority.
Flagging is different because it is a much stronger signal of violation of norms, however it is still mostly a signal from the HN user community.
The moderation balance on HN appears to be quite functional to me (although I'm happy with many guidelines that others fight against).
