What there contradicts what I said? I'm aware of innerHTML hacks that make it possible to work around but those are not valid attribute names. I'm not even against the syntax; i like it, but that doesn't change the fact that it is invalid html.
User pfooti's comment referenced the specification[1]. You said that a browsers' implementation of the DOM API proves that it is illegal. I then linked to an issue with a detailed discussion of how the DOM API isn't consistent with itself, much less the HTML specification.
