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.
I wouldn't necessarily present that as a good thing. If operating systems become incompatible with old software, that means that such software cannot be effectively preserved and may be lost to time eventually without a committed maintainer.
This is and always will be true about software. Progress sometimes means abandoning bad ideas, even ideas that were good at the time but are bad now that something else has changed.
Old Windows games generally don’t work on modern Windows without a virtual machine.