Needless to say, but I don't use vim or emacs. My editor can do that too, but it's not the point.

The subtlety of this is that it comments/uncomments a block. A block as defined by the language.

Not some manually chosen grouping of an artificial concept of 'lines';

Your point that it could be overlooked is valid, but if a block is going to be commented out (semi-)permenantly, then I would either put it into a pod comment, or physically remove it. The use of being able to comment out a block in a block-strucured language would be to test it's effect in the short term. A quick "what if" check whilst debugging. Easy to do and undo.

If, having tried the idea out, you decided to make it semi-permenant, then you could go back and use a macro to make it more distinctive.