lol, you should actually read the HTML spec, there are good explanations of all the elements. The whole point of defining semantics is that elements have meaning independent of their default appearance (or any appearance).

> I need to learn more about web accessibility, but if you completely ignore it (and other sane practices) HTML looks really simple.

Everything looks really simple when you ignore vast amounts of the subject and nuance.

Your rules don't mention keyboard or focus behavior, the only mention of either is the association between <label> and its <input>. <output> does have functionality, it's an HTML-native ARIA live region (that can be associated with a <label>).

https://html.spec.whatwg.org/multipage/