You can speed it up, and I've done that for some books, but I agree it's not the same. Specially for books from which you want to extract actual concrete knowledge, there is nothing like paper.

However, for the right books, audiobooks can be even better in my experience; books where you want some "wisdom" and feelings more than concrete stuff, and where a peaceful, somewhat-slow is appropriate.

I listened to Lab Girl, an intimate autobiography, read by the author, and it was fantastic. I am now going over a book on buddhism, and because I don't really care about remembering the details of Maharana's life, I love listening instead of reading. With such a book, reading faster doesn't seem to make much sense, I wanna go slow and savior its lessons.

In any case, it's been a good complement to my traditional reading; even when it isn't the best way to read a book, it's a fantastic way to make the most of commuting or doing chores.