Sometimes, being able to flip between two sections (comparing examples) or things a couple pages apart can be useful.
I remember having both PDF and hard copies of some RPG rulebooks, and it was almost always easier to find That Specific Thing in the paper book, once I was familiar enough with everything to use the contextual clues and page differences to find my way easily. Flipping between rules for {verb} and the list of valid {option} permutations is a similar case with tech books. Control-F helps, and so do bookmarks, but some things are easier with paper.
I remember having both PDF and hard copies of some RPG rulebooks, and it was almost always easier to find That Specific Thing in the paper book, once I was familiar enough with everything to use the contextual clues and page differences to find my way easily. Flipping between rules for {verb} and the list of valid {option} permutations is a similar case with tech books. Control-F helps, and so do bookmarks, but some things are easier with paper.