> One might think that as technology progresses more and more pieces of older technologies get revived and incorporated into the available tooling. Yet the very opposite thing happens: good and working parts are removed because the richest companies on Earth "cannot afford" to keep them.

I think it is because nobody, excepts a handful of people around the world, feels the need to use XSLT in lieu of CSS. Hence, CSS has evolved over time while XSLT has not.

This is how the world works: technology advances and old things become obsolete over time.