Hello aendruk! I guess you are referring to the animations? That's a matter of taste of course, and I took it to the extreme for the demo, to show what's possible. It's of course very questionable if this would be a good idea for every last website, but there are use cases where it can make sense (portfolio sites, for example)

You write this as if this is a Google-authored spec being shoehorned into W3C.

Most websites aren't going to use something like this. HN readers however may appreciate having the option and may put some thought into how this could be used well.