Thanks for replying to me! :)
I really didn't know about the recommendation process back then. It's pretty recent that I came to know about it. I am not sure if any of the suggestion helps at the moment since it's now a recommendation.
I am also sure that the working group must have thought about exhaustive scenarios so I may not even be making a point.
I know $ or @ couldn't be used since they were already getting used in preprocessors and @ specifically, I feel, wouldn't go with the existing syntax of CSS.
I met Chris Lilley few days ago and I came to know that $ could be used but it would create multiple problems.