Linearized (a.k.a. web optimized) PDF files only help for displaying the first page quickly. The rest of the file is still in pretty much random access order.

For what it's worth, there's a format for content like pdfs that's optimized for viewing on screens (as opposed to printing), djvu: https://en.m.wikipedia.org/wiki/DjVu

Oh, wow initial release 1998,now I'm feeling a bit old...