I programmed an app that was featured in several publications including the Washington Post and coverage by one of the writers for the Guardian. These favorable reviews led to a handful of sales. If this were a web app, these valuable links would have given my product a real boost.

With the app store, there's almost no way for a third party to influence the discovery of your app. Everything is sold through the app store and Apple holds all the keys to the kingdom. Who knows what mysterious process they use to select their favorites, but if they don't select yours, that's pretty much it. No recourse. The web, on the other hand is much more open and many different people can influence and contribute to a developers success.

So in a way you can improve your discoverability.

Edit to add: no judgment implied; I'm just curious.

Web apps don't hope that people stumble across them because there happens to be a centralized directory. The same active promotion used for web apps should take place for mobile apps.