I'm puzzled as to why Custom CSS properties, why not? would have been closed.
It does not seem to me like an open-ended question. It is a quite specific question about whether a certain feature (custom cascaded variables) is available in CSS or not, and (implicitly) if not, what workarounds might be available. Custom cascaded variables are actually a highly useful concept to the extent that an active working group is defining them as we speak (see http://dev.w3.org/csswg/css-variables/).
Unfortunately it is true that the OP did express his question poorly, with some elements making it seem like a bit of a rant. But that shouldn't change the fact that it's a useful question with potentially useful answers.
Disclaimer: I'm the one that provided the answer to this question involving "borrowing" an existing CSS property for your own purposes.