The possibility to show popups and popovers in browsers should be removed completely. There are little to no legit uses for them. Even reputable websites use them only to nag and annoy their users.
And don't get me started about Javascript. This is a plague, that causes more problems than it solves.
Popovers are CSS. Just a positioned element. And both up-and-overs are "legitimately" used as modals in apps.
Modals have a place, but like everything, they get abused by people with no idea about how things should work. But that isn't a good standalone argument for going back to pre-1997 CSS.
For all the time browsers have been providing this, no one's ever come even close to a good alternative.
That's why the JS-powered browsing experience will never go away, there's nothing like it for how people actually use computers now.