Yeah, the idea that it's some kind of foundation of the "open web" is quite silly.

I've used XSLT plenty for transforming XML data for enterprises but that's all backend stuff.

Until this whole kerfuffle I never knew there was support for it in the browser in the first place. Nor, it seems, did most people.

If there's some enterprise software that uses it to transform some XML that an API produces into something else client-side, relying on a polyfill seems perfectly reasonable. Or just move that data transformation to the back-end.