It was still there choice to deploy using iframes knowing that that was the way it felt. They could've use JavaScript to load the contents into a div or simply pushed so far users to a page that had nothing but the AMP content on it.
They left it severely sub optimal and decided that was good enough… making google significantly more annoying to use on iOS than what it was before.
That was the choice they made and stuck too. No options to turn it off, no options to do it a different way; you just get stuck with it.