Apple has much better backwards compatibility than Linux. The APIs haven't changed much since the Carbon->Cocoa transition 25 years ago, and SwiftUI (but that's optional). The impact of app sandboxing on developers was small - and sandboxing is universal on macOS now, there are only different levels of sandboxing but no such thing as unsandboxed apps anymore.

Apple's introduction of sandboxing to an app ecosystem designed without it was a masterclass in OS design that goes unappreciated in our industry. Nobody else pulled that off. It's no exaggeration to say that macOS is the most secure desktop OS by a long way, it's not even close. Linux trails far behind in third place. They achieved this via:

• Extremely long term planning (multi-decade timescales).

• Extremely good systems design.

• Incremental change, so developers always had a digestable chunk of work at any given point. The work needed was smeared out over decades, not drop-kicked onto people in ways that left them flailing.

• Good developer relations work to ensure devs got help quickly if they hit issues.

At no point has Apple's security team had to change course, reverse a prior decision, redesign a subsystem or fail to meet their goals. Everything has slowly clicked together so smoothly most people, even devs, didn't even notice it happening.

The sad thing is, the engineers who pulled this off are largely unknown. The head of Apple Security came from the One Laptop Per Child project and deserves a lot of credit, but much of the careful detailed design that makes the Apple security architecture work is done by unsung heroes. One guy was known only by the name "Perry the Cynic"!

Edit: I did some searches. Perry the Cynic was Peter Kiehtreiber, who seems to now be retired.