MacOS doesn't have to force it, users will gladly sign into their iCloud account. Virtually nobody uses the Windows Store, but the Mac App Store is a necessity given how restricted 3rd party apps are on macOS now.

Since when is the Mac App Store a necessity? It's still possible to download DMGs straight from the internet and install the .app by dragging it to /Applications

The only restriction to 3rd party apps are unsigned apps. Very rare these days, mainly small hobby projects. You can still activate them through the System Settings.