I classed that as something for the XML community to prioritize because implementations are so important to adoption for standards. If you design standards and want them to be used, at some point you need to figure out how to get resources to support development of key implementations, help major projects migrate to alternative implementations[1], or develop a replacement if nothing better is available.

The fragmentation you mentioned is part of what made this so frustrating: if everything you used was within certain toolchains, the experience was fairly good but then you'd need to use a different ecosystem and either drop back to good old XPath 1 or take on more technical debt. In many cases, the answer I saw people favor was leaving the XML world as quickly as possible, which is something the community has a strong interest in.

1. For example, Saxon added support for Python just a few days ago: https://www.saxonica.com/saxon-c/release-notes.xml Imagine if that had happened a decade ago and everyone who was stuck with libxml2 could have easily switched?