Agreed. Maybe I've had this wrong most of my programming career, but comments are usually for explaining the "why" of code if the code isn't that obvious by itself (and if this is the case, I usually try to refactor it first). It's rare that my comments ought to take precedence over the code itself.

If I do have something REALLYIMPORTANT (which is exceptionally rare), I plaster it all over so that it's practically not missable (esp. in code review). Sure, highlighting _that_ comment might help a bit during development, but I really don't think that use case is worth highlighting _all_ code in that case. But it could be a 'nice-to-have' for syntax highlighters.