What about Google killing XSLT? https://developer.chrome.com/docs/web-platform/deprecating-x...
Browsers also never added support for some of the most fundamental features to support XSLT. Page transitions and loading state are particularly rough in XSLT in my experience.
One bonus is that it will be easier to customize for people that know JavaScript but don't know XSLT (which is a lot of people, including me).
You'll still need to add a line to the feed source code.