Linux is a very different case. Linus is talking about the kernel breaking comparability with userspace. The kernel not breaking userspace is quite a different

Linux is a very different case. Linus is talking about the kernel breaking comparability with userspace. The kernel not breaking userspace is quite a different thing, and in particular when comparing the macOS kernel and Linux because Linux specifically has a stable ABI and macOS doesn't. On macOS it's libsystem that provides the stable abi and kernel interfaces change underneath. Beyond the kernel API's and libsystem you have the actual platform interfaces. Carbon is a deprecated framework and has been for a long time. If apps are using carbon then they must get updated, Apple has been warning about this since 2017 (beyond just the depreciation notice in 2012 and everything in between). And Windows95 apps almost certainly do not run unmodified... it's been awhile and things may have changed, but as I recall in XP (sp2, even?), they introduced the thing to run an app in compatibility mode and you actually select which is version to be compatible with. This works in some cases and not in others. Not to mention win32 support has held back Windows stability and progress for a long time.