There is no mention of HTML in these recommendations.
The recommendation is perfectly good for any API using HTTP as the substrate. The wisdom of using HTTP as a protocol substrate is questionable, but having made that decision the verbs it supplies work perfectly well.
Incidentally, the HTML living standard supports three form methods, not two: get, post, and dialog. Which rather reinforces the point that HTML != HTTP.
The HTML forms only support GET and POST. Try it.