I think the difference with Apple is that developers are not piggy bagging on Apple's infrastructure, but provide new kinds of services that Apple hasn't though

I think the difference with Apple is that developers are not piggy bagging on Apple's infrastructure, but provide new kinds of services that Apple hasn't thought of. Then when these services prove to be popular Apple implements similar feature and uses the notorious clause in their contract prohibiting replication of native functionality. This approach is much more dirty.