Sure you do and Ill tell you why..
a) When are you most likely to lose a disk or have other fatal hardware failure? The answer is during a boot-up, this is more often true if the drives have had a chance to cool down a bit.
b) What takes longer applying, for example, an RPM patch to apache and restarting the service or restarting the operating system? answer rebooting the OS.
That's not the way I meant it. I meant people care about how many hours per year is this web site available. Both the OS and the service affect that. IOW, I meant the OS is only part of the picture, and Microsoft has some things beyond the base OS that make it look even worse.