I believe that the idea is that if the ad is amp, you can be sure it will load fast and not impede the ux of the page, whereas if it's html/js, you can't. It isn't about whether it is cached or not.
But this sounds like a technical limitation that makes sense? This entire comment chain is mostly people interpreting the lawsuit as claiming this was a deliberate artificial delay for business reasons and getting outraged about that, not a technical issue.
It's a little murky. If the status quo comes with a cost, because of practical uncertainty, and you provide an alternative that eliminates the uncertainty (and the cost), and then you use the elimination of the cost to prefer your own method... at minimum, that feels "not fair."
If the top-line goal is to make the page as responsive as possible, I'm a little stumped as to what the alternative would be beyond delaying the loading of arbitrary html and JS. Can you think of a way to load arbitrary HTML immediately and not cause any page responsiveness issues on, say, a three year old Android device?
