Counterpoint: There are far more XML parsers and other XML tooling than HTML(5) parsers in the world. There is a reason for that, namely the HTML5 parsing algorithm.
I was always a fan of polyglot markup, a serialisation profile which is both valid HTML5 when send as text/html, well-formed XHTML when send as application/xhtml+xml and of course either when parsed in the absence of a media type. That seems to me as a good example of the first clause of Postel’s law.
I was always a fan of polyglot markup, a serialisation profile which is both valid HTML5 when send as text/html, well-formed XHTML when send as application/xhtml+xml and of course either when parsed in the absence of a media type. That seems to me as a good example of the first clause of Postel’s law.
https://www.w3.org/TR/html-polyglot/