You mean the hundreds of large companies that employ people to work on the Linux kernel because Linux is such an important part of their business?
That Linux?
What does a kernel have to do with the success on the desktop? If you want to talk about a complete OS, the kernel is but one piece and I challenge you to find a mainstream Linux distro that is more difficult to install than Windows.
I just built a new machine a few month back that I dual boot. I had OpenSUSE installed, fully configured including drivers, dev tools(even third party tools like RubyMine) and updated inside 45 minutes.
After 45 minutes, Windows 7 wasn't even 10% done with updates, much less have useful drivers and apps on it.
None of that has anything to do with the subject at hand: the Linux kernel is an example of a successful project where its devs are scattered to the wind, and unlike a company that lets its programmers work at home, Linux devs are employed by many competing interests, that Linus successfully wrangles them to keep the kernel functional and coherent is a testament to his abilities as a project manager.
Claiming that the Linux kernel isn't one of the biggest successes is to ignore the reality that it runs everywhere, from the smallest machines to the most powerful supercomputing clusters and is a success on two planets.