Actually, most of the weirdness comes from having been originally designed in a matter of 10 days by a single engineer working to accommodate a tight release schedule.
Remember, XML was actually designed for use cases like this, that’s why it came with XPath and XSLT, which let you make it executable in a sense by performing arbitrary transformations on an XML tree.
Back in the day, at my first coding job, we had an entire program that had a massive data model encoded in XML, and we used a bunch of XSL to programmatically convert that into Java objects, SQL queries, and HTML forms. Actually worked fairly well, except of course that XSL was an awful language to do that all in.
React simply figured out how to use JavaScript as the transformation language instead.