But the point is that XML syntax is still a thing, supported by all browsers (and it’s reasonable to expect that support to remain as long as HTML remains). See

But the point is that XML syntax is still a thing, supported by all browsers (and it’s reasonable to expect that support to remain as long as HTML remains). See also https://html.spec.whatwg.org/multipage/introduction.html#html-vs-xhtml https://html.spec.whatwg.org/multipage/introduction.html#htm...: > When a document is transmitted with an XML MIME type, such as application/xhtml+xml, then it is treated as an XML document by web browsers, to be parsed by an XML processor. Authors are reminded that the processing for XML and HTML differs; in particular, even minor syntax errors will prevent a document labeled as XML from being rendered fully, whereas they would be ignored in the HTML syntax. HTML does use an XML base (elements, attributes, namespaces, &c.), it just doesn’t use an XML parser most of the time. But the XMLness is easily observed in various DOM APIs.