I think you are missing the difference between resize (the window) and re-flow (the contents to fit the window)
Try this on your PC:
View a document (book) with your favourite PDF viewer.
(turn off all the sidebars and stuff)
Now reduce the window to the size of your book reader screen.
What do you see? A small image
Zoom in you say OK, Now you have scroll bars R-L, U-D to use your mouse on.
Where is the Mouse (joystick) on you PEz?
You can not scroll around.
Do you enjoy reading with a left-right shift (and the e-ink flash every shift)?
Re-flow is the solution (and the very difficult problem) to a small screen being used with a document formatted for sheet paper of a different size and aspect ratio (a paperback text area is 10:16 and your PEz is 3:4 )
HTH