The point of the 11-star experience is not to actually target an impossibly perfect and amazing experience every time.

The idea is to acknowledge that 5 stars is what we tend to rate something that goes perfectly well without complaints, and as a product design exercise it fails to be a good target.

So Chesky's idea is to figure out what would make something so absurdly good that someone would rate it more than twice the usual "no complaints" rating - and then work backwards and figure out what is in between the 5 and 11 star experiences. You're never trying to reach 11 by design, but maybe you can target 7 or 9 as an aspirational goal, and thinking through this as a design exercise can help you identify user motivations more effectively.