I can buy that some of the spacial and tactile aspects of a real book can help with recall, I also wonder to what extent it has to do with the type of screen. I’ve found I dislike reading any long form material on emissive screens, whether on a computer or a tablet or a phone. Even when using “e-reader” applications, I can’t seem to get into reading a book on those screens. But on a whim some years back I bought a Kobo ereader at a flea market and it has done wonders for getting me back into reading books for fun. No it’s not quite the same as paging through a real book, but I can actually stand to spend hours reading off the e-ink screen in a way that for some reason just doesn’t work for me on traditional displays.
I'm skeptical there actually is a difference. I've compared my iPad with the white point, brightness and color filters set for comfort and it's no worse for reading than a Kindle Paperwhite with the reading light on (which you usually want for higher contrast). I'd attribute more of that fun reading experience to it being a single-purpose device more than the quality of the screen.