I am reminded of when Google attempted to kill MathML a few years ago because it was complexity and no one was using it (… because Chromium didn’t support it—all others did). There was widespread rebellion, and it actually led to Igalia implementing it and Google accepting and shipping it.

It wouldn’t surprise me to see a resurgence of interest in XSLT after this, if only for formatting Atom/RSS feeds.

(BTW, prefer Atom unless you’re operating in podcasting, it’s far more sane in ways that occasionally actually matter, and everything supports it except in podcasting which Apple ruined. If you want a featureful stylesheet to look at for reference, mine is the best I know of: https://chrismorgan.info/atom.xsl, https://temp.chrismorgan.info/2022-05-10-rss.xsl.)