One of the stated goals is to make html a true hypermedia language right? That's really pretty much it.
A lot of these objections sound like "why bring these functions into JavaScript if JQuery already exists? Why do we need CSS Grid if bootstrap already exists?" Because those are arguably add-ons meant to deal with the deficiencies of the original technology. Fixing that technology is a better place to be.
Except that it doesn’t fix the technology, it gives the appearance of augmentation via a bunch of JavaScript. Seems more like the jQuery and Bootstrap of your examples.
Sure, you don’t have to look at it, you just program against the interface. Just like you don’t have to look at the internals of jQuery - you just program against its interface.
A lot of these objections sound like "why bring these functions into JavaScript if JQuery already exists? Why do we need CSS Grid if bootstrap already exists?" Because those are arguably add-ons meant to deal with the deficiencies of the original technology. Fixing that technology is a better place to be.