> The thing is, xslt isn't underpinning much of anything
An awful lot of stuff depends on xslt under the hood. Web frontend, maybe not much any more, that ship has long since sailed. But anything Java? Anything XML-SOAP? That kind of stuff breathes XML and XSLT. And, at least MS Office's new-generation file formats are XML... and I'm pretty sure OpenOffice is just the same.
Let me rephrase that, client side xslt in browser isn't underpinning much of anything. I agree there are more uses in the enterprise world, although i think most of your examples are more XML not XSLT (people really shouldn't comflate the two. XML underpins half the world). I've never heard of anyone using xslt on a microsoft office docx file.
I'd also assume the java world is using xalan-j or saxon, not libxslt.
An awful lot of stuff depends on xslt under the hood. Web frontend, maybe not much any more, that ship has long since sailed. But anything Java? Anything XML-SOAP? That kind of stuff breathes XML and XSLT. And, at least MS Office's new-generation file formats are XML... and I'm pretty sure OpenOffice is just the same.