> You just downloaded a single .exe file, and it ran self-contained, with all its dependencies statically linked, and it would work on practically any system.
Yeah, but try that today (and even by 2010 that wouldn't work anymore). Windows will show a scare popup with a very hard to find 'run anyway' button, unless your application download is above a certain 'reputation score' or is code-signed with an expensive EV certificate.
> On MacOS, the user facing model is still that you download an application, drop it in the Applications folder, and it works.
Not really, macOS will tell you that it cannot verify that the app doesn't do any harm and helpfully offer to move the application into the trash bin (unless the app is signed and notarized - for which you'll need an Apple developer account, and AFAIK even then there will be a 'mild' warning popup that the app has been downloaded from the internet and whether you want to run it anyway). Apple is definitely nudging developers towards the app store, even on macOS.