I'm more concerned as to how it's increasingly impossible to buy an old copy and install it; the app store will only show you the latest version (and even for o

I'm more concerned as to how it's increasingly impossible to buy an old copy and install it; the app store will only show you the latest version (and even for only the latest OS version), and the installer might even refuse to install, having detected a more recent version. You basically have to pirate it in order to do these kinds of shenanigans.