The point is virtual selectors and using Javascript for styling both have very poor performance characteristics, and both are A. ubiquitous and B. hacky kludges

The point is virtual selectors and using Javascript for styling both have very poor performance characteristics, and both are A. ubiquitous and B. hacky kludges driven by the excessively limited nature of CSS as originally designed. I'm probably out of my depth here, but what do you mean by the style sharing cache? I mean, any kind of file can be cached by the browser, including Javascript. And presumably browsers could've implemented optimizations (with or without the aid of hinting annotations) to identify those DSSSL functions that need only be evaluated once. (BTW, like the author of the article seems to, I actually think that PSL looks like the best of the CSS alternatives he lists).