AMP also forces precalculated layout of the page and disables bad CSS selectors. You can take a page, take out all the JS cruft, and put all the resources on a

AMP also forces precalculated layout of the page and disables bad CSS selectors. You can take a page, take out all the JS cruft, and put all the resources on a CDN, and still end up with mobile layout adding 500 milliseconds to the initial page render, or more, if relayouts are triggered during render. The majority of regular web developers aren't even aware of layout costs.