I believe that to understand GPL and FSF philosophy, you have to look at software from the point of view of the
end user, not programmers.
> There is some value to having windows itself, but the more valuable thing is the horde of programmers, and all the other resources behind it.
This is partly true. What's valuable is for code to do things for people. For that to happen, you need programmers who can make that code, and maintain it over time. The way companies make money on proprietary software is by controlling the intersection - they control the access to code and programmers who can work on it, so if you, as end user, want your computer to do something, you have to pay them. If you want the program to do something else, you have to pay them (or their partners, friends, subsidiaries) to make the modifications/extensions.
GPL exists to defeat this stranglehold. It does it in two ways. First, like permissive licenses, it ensures you can modify the code yourself, or commission some programmers to do that for you. Secondly, unlike permissive licenses, it ensures that you can't just turn around and lock down your improvements, preventing other end-users from doing to the improved version the same thing you just did to the base version. In this way, it ensures the money can only flow from users requesting work to programmers doing the work - it removes the ability to seek rent for the work already done. It removes control over users from the hands of companies and software developers.
Permissive licenses are obviously preferred by software industry, because they give more control to us, software developers, at the expense of end users.