A better example would be Google. What would happen if Google tried to own some of the dollars that flow through the organic search channel? /shudder
It is a pretty good comparison as long as App Store is the only way to install anything on iOS
It may strike you as obviously false, and it may well have been so two years ago, but when I got my new iPad after moving to another country I've spent about twice as much time getting iTunes to let me pay for apps in foreign App Store than I've spent researching jailbreak options and caveats and then actually pwning the device.
So no, App Store is far from the only way to distribute iOS software, even though it still is the default and sometimes the only apparent way.
From my experience, it turns older iPhones into a stuttering laggy mess and breaks visual voicemail, and makes you paranoid about every iTunes update.