I don't think it was ever "purged" - I mean, which modern browser doesn't handle XSLT 1.0?
Nor did the spec itself stop evolving. The problem is that the browsers have deprecated the technology before XSLT 2+ could be adopted.
> which modern browser doesn't handle XSLT 1.0?
I know it depends of the definition of "modern browser", but I'm fairly sure that MSIE and pre-chrome Edge had lost support for it at some point, since MSXML stopped being shipped with them.
I honestly don't know what the current state of the art is, but Firefox doesn't do native XSLT anymore afaik (yes, you can do it in JS, but it's an extra step).
Somewhat ironically, the semantic web was initially supposed to be built on browsers making calls for XML data (the X in Ajax) to then be displayed via XSLT. This model failed to gain adoption mostly because, let's be honest, XSLT is just blooming hard.