The point is that you don't need the very latest version. The 20 years old version is enough.
And the default Python XPath support is severely limited, not even a full 1.0 implementation. You can't use the Python XPath support to do things like `element[contains(@attribute, 'value')]` so you need to include an external library to implement XPath.
I think simplicity is better. That's why Json is used nowadays, and XML is not.
[1] https://www.w3.org/TR/xpath-31/ [2] https://jackrabbit.apache.org/oak/docs/query/grammar-xpath.h...