Evils of dynamic content

Remember the dial-up-served HTML 0.x age, where pressing back button instantly brings you to previous page? Nowadays most of the content you see on the internet are actively served i.e. they are not loaded from static .html files, so sometimes we need to wait for the browser to revalidate the page before loading from cache. We are trending further away from static serving, and going further into dynamic pages, but what haven't we lost something along the way?