Less is a way to signal more, like restaurants which only have 5-6 options available, the impression is they have less so they must be doing more with what they have.
Also, it unifies people around a book making a natural environment for book clubs to emerge from and it reduces the anxiety of pretending to look at the selection when you have already decided not to buy.
What a great idea!
Given the complex logistics of storing and preparing ingredients in a restaurant, having only 5-6 options is not just about "giving an impression", but is an actual good sign about the freshness and quality of cooking.