The simple point of this excellent commentary by Aaron Levie, CEO at Box, Inc. is that making promises is much easier than keeping them. A less politic way of putting it would be that expectations are like babies; easier to create than to maintain over the long term, but so very rewarding if done right. OK, that was clunky, but you get my point.
I think this idea of making few (maybe even just one) explicit promise to your customers, and then exceeding it, is a great model for success. Why doesn't In-N-Out sell hot dogs? Because they are laser-focused on nailing their existing limited menu, and providing unparalleled customer service.