Basically, you're paying for curation. I buy cookbooks because I'd rather have one recipe that I have some faith will be good than ten recipes that might sort of work. Having a pile of maybe-good recipes is like having a bunch of StackOverflow answers to things that are sort of related to my problem.

I also still buy travel guides, for the same reason. Paying twenty bucks for a dead-tree guide to the place I'm going means I don't spend half my vacation reading Yelp and TripAdvisor reviews.