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.
But this isn't a discussion about whether or not modals are good idea. The OP was arguing —without any idea what the mechanics are, I'm sure, because that's how we decide how technology works these days— that CSS should not be allowed to layer and position one thing over another.
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.
What gets me, and makes me sad, is how javascript-enabled browsers (and really the magic happened with IE and its XMLHttpRequest) are clearly addressing a need the vast majority of the computing world has: running applications simply (without installing, because that's been made complicated) and with a reasonable expectation of security (sandboxed).
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.
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.