It's one strategy. The other is opening it up so much that no one breakout distribution, application, or interface could possibly emerge "victorious" (meaning, the vast majority uses it), which is what Linux does. There is so much room for experimentation, so many flavors and choices and configurations and ways to do it, that no one but the most hardcore and devoted users can seriously figure out how to do things with any respectable degree of confidence.

I've run Linux on the desktop in one form or another (laptop, desktop, or server) since Red Hat Linux 6.2. That was over a decade ago. And, guess what? We're still fighting over GNOME vs. KDE (or fluxbox), and apt-get vs yum (or port), .rpm vs .deb (or .tar.gz). You still can't grab a package from Ubuntu and install it on your Fedora box (well, not without a tremendous amount of headache), and if you go strictly upstream, you have to be at the terminal every time a new version comes out (./configure + remember the build options you want, make, make install).

Windows, unfortunately, is in the middle, and it's still, 15 years later, a virus-prone rooted-zombie mess, albeit with a supposedly pretty good modern browser coming real soon now.