If publishers behaved themselves then adding Javascript for optimization would be odd, but they don't behave: http://www.nytimes.com/interactive/2015/10/01/busi

If publishers behaved themselves then adding Javascript for optimization would be odd, but they don't behave: http://www.nytimes.com/interactive/2015/10/01/business/cost-of-mobile-ads.html?_r=0 http://www.nytimes.com/interactive/2015/10/01/business/cost-... ...but overall I agree it does feel strange to have worked to hard to have highly capable browsers and then only use a tiny subset of functionality. From: https://www.ampproject.org/docs/get_started/about-amp.html https://www.ampproject.org/docs/get_started/about-amp.html AMP JS The AMP JS library implements all of AMP’s best performance practices, manages resource loading and gives you the custom tags mentioned above, all to ensure a fast rendering of your page. Among the biggest optimizations is the fact that it makes everything that comes from external resources asynchronous, so nothing in the page can block anything from rendering. Other performance techniques include the sandboxing of all iframes, the pre-calculation of the layout of every element on page before resources are loaded and the disabling of slow CSS selectors. To learn more about not just the optimizations but the limitations, read the AMP HTML specification.