Platform specific does effect the ability to be a "killer app".
Ms Windows being a killer app was in a completely different time period. Any app that has to have game changing ability has to be cross-platform or perhaps run on the web. Anything else and its not a "killer app". It might get the bills paid and be profitable but "killer app" it ain't.
The definition of a killer app is one where somebody will buy the platform just to use your app. By its nature it makes you choose a platform.
http://en.wikipedia.org/wiki/Killer_application
Ms Windows being a killer app was in a completely different time period. Any app that has to have game changing ability has to be cross-platform or perhaps run on the web. Anything else and its not a "killer app". It might get the bills paid and be profitable but "killer app" it ain't.