They are not meant for comics, thats simple.
PDF is meant for TEXT-ONLY, like actual e-books without a single image
1.
Does PDF save the page number?
No.
You exit a PDF on page 69, and open it again, it's on page 1.
No matter which viewer you use
2.
Does PDF save the window configuration?
No.
You exit on 85% size (because font-size etc.), and open it again, and it's back to Default (for me that's roughly 200%, a nightmare).
No matter which viewer you use
3.
Does PDF save that you exited during fullscreen?
No.
You exit during fullscreen, or any other mode that removes sidebars, titlebar, statusbars, etc. then you open it again and all the bars are back.
No matter which viewer you use
Comics are meant to be viewed with a Comic specialist program,
Comic Book Reader is probably the most known
(since it combines all 3 points I mentioned)
And the worst part of it all is that when you extract most of this collection, you get TextLess images, sometimes not even empty white bubbles are there (they get removed as well during image extraction).
Before I saw this happen "here" I didn't even know, had no idea, that GhostScript or whatever is used can add empty white speechbubblefields on top of images