Most Linux distros have a mothership in the form of the package repositories and the signing keys thereof. Doing without would require a more decentralized system that would be harder to engineer, unless you want to go back to the days when all software updates were piecemeal and manual.

I would actually say that Linux distributions pioneered the app store concept via "yum install" and "apt-get" and such. Linux is certainly the first OS where I can remember seeing a centralized app repository you could pull from with a single command.