The goal is admirable, but the execution and implementation is, in a word, absurd. From the XMLUI website:
> XMLUI provides the glue that binds the React ecosystem into a declarative model.
This negates the raison d'être of React, which is to bring the development style of immediate mode UIs to the browser—that's the fundamental driving factor behind the creation of React. Components are incidental. (Web browsers in fact do components just fine, with native support for custom elements and shadow DOM—which, along with flexbox, is a descendant of XUL, the other 90s-era technology that worked the way the XMLUI authors lament isn't around.)
The purpose of React was to bring the development style of "immediate mode" UIs to the browser[1], which for better or worse inherently has a "retained" model of the UI that developers writing in-browser apps would have to deal with. So now with XMLUI, you have React trying to paper over the fundamental nature of the DOM to make it feel like it's immediate mode instead (and all the fakery involved with that), and you have XMLUI choosing to build upon React and do these retained objects instead—aligning with how the browser actually does things underneath React!
The "The Backstory" section on the XMLUI landing page is worth a look and really drives the point home (along with Jon's admission in his blog post that he's never been a React developer):
> It began with a relatively small effort to add web-based admin interfaces to some of the company’s products. This resulted in the core engineering team — experienced backend developers whose interactions with UI technology were limited to old-school battleship-gray Visual Basic, Delphi, or .Net/Winform — being surprised by the complexity of modern web development.¶ Calls for simplicity and easy/intuitive tool support were met mostly with blank stares from the React guys on the other side – and the designer, UX guy, and JavaScript folks on the server side of things.¶ But the /n software team refused to take no for an answer, and more than two years of work from a team of Javascript/React wizards resulted in the new semantic layer that is XMLUI.
"Simplicity" this is not. Ditch React. You don't need it. You're actively working against it. (And worse, it looks you've put yourself at the whims of hired "experts" who exemplify the stereotype of the React-only programmer who never learned the fundamentals, and in this case can't even spot that you're asking them to undo React.)
1. https://www.youtube.com/watch?v=8ZlN07IvoPI&t=2131s>