Web designers think web pages are like magazines, that they get to dictate layout. And most of the development in web browsers and standards lend themselves to that view.
As a user, OTOH, I think of web browser as my User Agent. I accept "polite suggestions" from the website, but ultimately I should have the last word about how it looks. The web was originally designed to work this way.
I'm not sure how to reconcile those views. I'm obviously biased towards the second, and I'd love web developers to be told to bite it. But this, unfortunately, won't work, because there are strong business pressures to the contrary.
A) Developers hack their way around to the result they want anyway, or
B) Users of that browser lose a chunk of the experience.
Either way, everyone loses.