> You are allowed to just make up elements as long as their names contain a hyphen

RIP any semblance of using meaningful tags for machine readability I guess.

it's a lot more readable than a bunch of divs

if an element that semantically fits your needs already exists you don't need to make up an element in the first place

Hmmm, I thought you had to register these with JS first, but my browser seems to recognize them.

And even if they don't contain a hyphen! You can just <use> <anything> <you> <want>

The soft-requirement for hyphens is a form of namespacing: nothing precludes whatwg from adding <use> or <want> elements to HTML in the future, and that would conflict with and possibly break your page.

To prove your point, <use> already exists although in SVG. https://developer.mozilla.org/en-US/docs/Web/SVG/Reference/E...

What's the use case for machine readability these days?

We could have that with XHTML+DTDs...