The guideline is not about criticism, it's about a particularly tedious form of repetition. It's a bit like its neighbor, the guideline that asks people not to comment on comment voting in comments.

HN users are not shy about making criticisms, and any HN user who has one can easily find a more substantive way of making theirs. Actually, if a comment showed up that broke that guideline and had something genuinely interesting to say, it wouldn't be a problem—it's just that they never do.