Ah, I see.
What's so funny about this is that XML is absolutely brimming with rich namespace solutions for all the problems you don't have. For example, if your users ever want to blithely roll their own "href" namespace, don't worry! The xmlns http://www.w3.org/1999/xlink is there for them to safely disambiguate all the custom:hrefs from the xlink:href things!
Meanwhile, in 2026 you've got two designers who each use their own "bgcolor" and XML is like, "Nope!"
Digression-- I just checked MDN and apparently xlink is deprecated! This makes me want to write alternate history from the mid-2000s about the href wars: XML namespacing parties where front-end designers would mash up dozens of href namespaces in the same document.