You can write scripts to transform XML documents as well.

True, but I don't want to. And that is the biggest barrier of all.

I was going to say what GP said, but, yeah, XSLT is just no fun to write by comparison to SQL.

Hardly anybody was using XSLT even when XML was all the rage. Python scripts work just fine.

XSLT 1 was very limited. XSLT 2 was too late. That's my take. I actually like XSLT 2, but it's so verbose... -- it's horrible.

Once in a while I dream of adding proper XML support to jq just to be able to use jq as a pithy alternative to XSLT.

XQuery is easier and can be fun to use!