Actually, Apple has been a follower.
Ubuntu and the Linux world in general has had app-stores long before Apple came to the party.
The Apple app-store is nothing more than a Sony'fied software repository.
Where Apple have succeeded while "The Linux scene" has floundered is, Apple have put the app-store, physically, in peoples pockets. Sony/Sharp could have done it sooner, if they'd made better hardware and been cohesive with their late-90's/early 21st-century Linux/e-Tron strategies, but make no mistake, Apple are a newcomer to the vendor-supplied online software repository scene. Albeit, a very powerful, sexy, one.