> 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>).
I’ve noticed that discussions of semantic meaning of tags often contain the word “feel.” Nothing wrong with that, taste matters, but it does point to the non-functional goals that are being pursued when people disagree.
<ol> vs <ul> - they are both ordered, because markup is ordered. One gets decorated differently than the other by default. Is the difference semantic or typographical?
<ul> Players
<li> Alice
<li> Bob
<li> Carol
</ul>
<ol> Leaderboard
<li> Bob
<li> Alice
<li> Carol
</ol>So is it a decoration hint? Or is it actually semantic? And what system is interpreting the semantics rather than the visual presentation?
In theory.
In practice, no one cares about semantics and the tags are chosen based on how a target set of browsers happens to display them.