It doesn't sound like ending annual updates would change what you want. Slowing down public releases without any other changes to engineering focus just means that the updates are bigger, and break more stuff each time they do come out.
Conversely - on a platform, smaller updates that break fewer things encourage third party developers to actually budget to maintain their software.
It sounds like what you want is more engineering focus on existing feature polish and stability rather than introduction of new features. This is not a new problem, and not one unique to Apple (points to Google's culture which encourages new products over maintenance of current ones).
Apple actually does seem to be focused on supporting maintenance better - for instance, by porting a significant portion of their own apps to SwiftUI, to unify under a single codebase (and single team) responsible for them. This gets marketed in a number of ways, including "desktop-grade" apps on iPadOS.
You also see a reduction of 'changes for change sake'. Even the large UI changes to macOS 11 and iPadOS were really about trying to make common codebases feel more 'natural' shared across those two platforms. Stage Manager is definitely a more strategic effort toward that goal as well - shipped with noted deficiencies, but you have to start someplace.
But that isn't polish and stability for the current codebase, it is investing in a new codebase which may not have the same stability or polish at first. Thats the rub of continuous development - continuous improvements toward stability can still have a destabilizing effect.
If you aren't willing to accept that, then what you are doing is software maintenance, and your speed will gradually decrease, your development costs go up exponentially, and you also lose some ability to retain engineering talent. Nobody wants their career to be watching a state-of-the-art codebase gradually turn into COBOL.
