Makes sense. F'rinstance my local credit union has an app for online banking. That means, right away, that the entire potential audience is only :: detour to look up membership :: 60,000 people hmm, much like my own site rather than, say, half the population of the planet. That's quite a few decimal places.
Many apps have only proprietary value for the customers or visitors of a particular site or B&M business but they are in the app store to meet requirements. Rather than a feed reader with a bookmark to partial content, some sites (think art and photo sites) offer more or better images to their app's subscribers. Some restaurants offer an app with updated menu info and a simple reservation option. These aren't for mass consumption but Apple requires developers to have apps cleared via the app store so malicious junk doesn't get distributed.