If you follow the "API war" hyperlink, it's under the heading "It's Not 1990".
When consumers are upgrading their hardware regularly as they were in the 1990's, then developers can disregard the notion of users "upgrading" their software.
Instead they can just write applications targeting new hardware. It does not have to run on older hardware.
The user will be compelled to upgrade the hardware and, in the case of Windows, by default they get the new software. The example cited was Excel versus Lotus123.
MS also benefitted from hardware sales through agreements with the OEM's.
what do you mean by that?