Really you should look at it from both sides as with any business.
Without Apple there would be no App Store for the devs to write for (they could of course write for other platforms)
But without the devs, Apple fails as it has no app store.
Imagine just how long the iPhone would last if every single dev pulled their app and moved to Android.
The devs have all the power in reality, it's just, like any group of "workers" getting the individuals into a group is the only way the other side takes any notice.
Without Apple there would be no App Store for the devs to write for (they could of course write for other platforms)
But without the devs, Apple fails as it has no app store.
Imagine just how long the iPhone would last if every single dev pulled their app and moved to Android.
The devs have all the power in reality, it's just, like any group of "workers" getting the individuals into a group is the only way the other side takes any notice.