Users don't always have write access to the apps.
Mostly like a mini home folder in each app.
That would have been an interesting decision, quite hacky maybe, but incredibly ergonomic. And that would have changed one of the biggest flaws of Mac OS into one of its biggest strengths.
The best counter argument to this though is that Apple haven’t shipped a native “uninstall” action which can optionally strip caches, config and other state when an app is removed. That’s the real issue I see here.
They do the same shit as every other OS : files with a more or less random place in the home folder.
So it's more akin to linux where removing a package lets the garbage in the home dir. On Windows it's not THAT MUCH better, it's just that removing app can be so stupidly complex that the concept of uninstaller had to be created, and it happens that some uninstallers are also helping to remove user files.
Of the three, it's the same shit, it just happens that in Windows it's so shitty that the hack we found to circumvent (the uninstallers are fucking executables with logic to remove another executable, that's stupid) made the situation less shitty.
MacOS is regarded as shit because they DID think about a nice way to sore and expose an application (a Mac OS program is just a folder named "MyApp.app" in the /Applications folder containing all the binaries and assets) but they didn't really care about where to store the application data (in fact it exists but it's not enforced and never cleaned).