It’s been years since I’ve touched it, but clicking the congressional bill XML link and seeing a perfectly formatted and readable page reminded me of exactly why XSLT has a place. To do the same thing without it, you’d need some other engine to parse the XML, convert it to HTML, and then ensure the proper styles get applied - this could of course be backend or frontend, either way it’s a lot of engineering overhead for a task that, with XSLT, requires just a stylesheet.
edit: I see Simon mentioned it - https://simonwillison.net/2025/Aug/19/xslt/ - e.g., https://www.congress.gov/119/bills/hr3617/BILLS-119hr3617ih.... - the site seems to be even less popular than Longhorn Steakhouse in Germany.
My guess is that they'll shuffle people to PDF or move rendering to the server side, which is a common (and, with today's computing power, extremely cheap) way to generate HTML from XML.
Further, PDF and server-side are fine for achieving the same display, but it removes the XML of it all - that is to say, someone might be using the raw XML to lower tools, feeds, etc. if XSLT goes away and congress drops the XML links in favor of PDFs etc, that breaks more than just the pretty formatting