I'm with you this seems to be reimplementing the wheel but, recently XSLT has been widely deprecated. And the (sole?) maintainer of some very core infrastructur

I'm with you this seems to be reimplementing the wheel but, recently XSLT has been widely deprecated. And the (sole?) maintainer of some very core infrastructure for that is paused or archived or something that will slow/block features and fixes. So, is a revamp, new code with less baggage, doing the same-ish thing. Then in 20 years it will have the baggage and we'll get a new one. Queue the Xkcd about infrastructure.