> switching between X pages before and here, highlighting quickly, making quick notes on the side and so on.
Any PDF reader I've used will do those things, iirc.
> I can fold or flip a page so, that I can quickly view certain parts of the second page while I read the first one.
With PDFs, you can open it in as many windows as you like and arrange them for simultaneous viewing on your screen. Open a copy on another device too if you like.
I'm not saying books have no advantage, just not for those functions IMHO.
> switching between X pages before and here, highlighting quickly, making quick notes on the side and so on.
Any PDF reader I've used will do those things, iirc.
> I can fold or flip a page so, that I can quickly view certain parts of the second page while I read the first one.
With PDFs, you can open it in as many windows as you like and arrange them for simultaneous viewing on your screen. Open a copy on another device too if you like.
I'm not saying books have no advantage, just not for those functions IMHO.