If I'm wrong about what you're getting at, feel free to provide an example.
But I think what you're saying is that instead of reviewing like this (sorry, psyanic, but you were the only one I could think of to get any example from!) you mean more like this (sorry, Bay, but you were the only example I could find!)?
Honestly, the "constructive comment" rule wasn't put into place because I was expecting people to post beta-like reviews. It was put in place so that people can know that their fics are being read, as all the reviewer needs to do is just mention something specific about the fic they're reviewing. Like with Bay, she made a few short comments about IceKing's fic. Not a lot of in-depth ones and she never quoted the fic, but he knows that she read his fic because she mentioned something specific about it.
Maybe this will be something to discuss in psyanic's idea here: