Spaced repetition systems have gotten way better

It's always been extremely funny to me how arguments like this and from the curl author go. "Yes, I had to change curl away from strictly accepting two slashes, for web compatibility. But `while(slash) { advance_parser() }`? That's completely unreasonable! `while(slash && ++i <= 3)` is so much better, and works almost as well!" Ok, whatever...

As for your claim about living standards, I'd encourage you to read https://whatwg.org/faq#living-standard

Also see the spec PR from WebKit: https://github.com/whatwg/html/pull/9546

Almost, it's `switch=""`, `checked=""`.

The issue with a single global event handler is discussed here: https://github.com/WICG/close-watcher#a-single-event

If you use popover="", you get the kind of functionality you're discussing for free. For <dialog>, the discussion is in progress and reaching a conclusion: https://github.com/whatwg/html/issues/9373