I had a boss (when I was just out of HS way back when...) that tried to require that too... Until I started writing the annotations in code that only myself and one other person could decipher

Coders don't need to comment every single thing, just basics functions (i.e. this function does this). If you need every line commented, you shouldn't be messing around in there.

Knowing how to do the above is basic css. In my opinion but if someone doesn't know how to do the above they shouldn't not be working on the css file at all.
Further no webdesign creates a css file in mind with 'others my need to learn css from my flie' so I will fill it full of comments, that is utter nonsense, after all there are enough places on the web to learn css.