"Love" the latest fad there, where JS is used to turn a site into a flip book as you scroll down. This by having new "content" come up and cover the old stuff as if you were flipping pages.

Agreed. I had to create a 'modern' design website for a client with all the fullscreen images included. I hate those websites but had to do the job. So I decided to do it all myself. And guess what: 80% compression for a fullscreen image is enough, people don't notice it. All animations were done in CSS. And then I wrote some small javascripts for those hide on scroll, paralax images and other scripts.

Kept the page size below 1MB, server time around 0.3s (ProcessWire), onload below 3s.

It's still not optimal, but when you dump all those bloated Javascripts and compress images a page should not be 10MB.