They control the ecosystem in the way that they provide what hardware is new on MacOS and what capabilities it has.
So if any developer wants to support modern devices they have to port to that new hardware. They don't have any choice, if they want to stay relevant.
What may seem easy to an outstanding person is most definitely not easy in reality.
There is so much more complexity involved in this, and not even speaking of the whole corporate nightmare new features have to go through.