In the Scott Forstall days, there was a distinct iOS team (Scott) and a distinct OSX team (Craig). now there isn't.
In the Scott Forstall days, there was a distinct iOS team (Scott) and a distinct OSX team (Craig). now there isn't.
Frankly, maybe that's exactly the problem. He left in 2012, and that definitely feels like around when things started going downhill.
I don't know what stuff is like under the hood, but from a user perspective, iOS and macOS are two very different platforms that are good at very different things. I'm sure there is a lot of tech that can be shared between them, but some individual focus would likely be beneficial as well.
And if those "other responsibilities" are iOS, tvOS, and watchOS, then there is no "macOS team." There is the software engineering organization.
Apple slices up departments by function, not by product, which is why there are organizations under Tim Cook such as Software Engineering, Hardware Engineering, Internet Services, etc. Everyone and no one is responsible for shipping all the products as a result of this structure. Software Engineering in particular is responsible for all of the operating systems that powers Apple hardware.
Similarly, this is how smaller departments under each SVP/C-level org are subdivided, and so on to the team level. Each team may be responsible for a particular product, which includes all the experiences for that product across operating systems. There is no single engineer responsible for just macOS/iOS/tvOS/watchOS. Everyone is responsible for everything, and similarly no one is responsible for anything.
Apple's structure is unique compared to other companies, and contrary to how most are run, which probably contributes to your confusion.