Of all the criticisms of the Windows platform I recall, I don't remember anyone complaining it was "closed system".
In fact, the opposite problem made it a haven for malware and viruses.
In fact, the opposite problem made it a haven for malware and viruses.
In terms of the ability to run random bits of code on it, Windows was highly open. Perhaps too open when you take into account not only malware, viruses, and spyware, but the various crapware/bloatware OEMs would pile onto their Windows preloads.
Arguably some Linux distros, with their comprehensive archives, though with rules for what could or couldn't be installed (based on licensing requirements) were more "locked down", though in truth you're more than open to install third party from sources, as binaries, or any other means you care. In practice, I prefer sticking largely to my distro's own archives and installation tools, precisely because the software is both more vetted and generally behaves far better.
So, no, your criticism really isn't valid.
Now, I can put ubuntu linux on my machine - for free (or in my case, preloaded from DELL at a discount over windows) and get a million different toolchains with free documentation online.
Windows was as open as open can get, in the sense of, "Do I need to ask anyone's permissions to create, install, and sell a binary for this platform?"
i guess the part of my complaint that had the most to do with 'closed' was the MFC/developer licensing part. I knew enough to know there were APIs lying underneath that weren't exposed to me that I could do awesome stuff with if I was able to see it. At least with BeOS it "felt" like the most important part of the API were exposed - and with linux I know that they are in principle, even though I never use them.
Microsoft sells and supports development toolkits, and they happen to be better than a lot of the free ones. I bought PyCharm for Linux -- that doesn't make it closed.
The only thing closed about Windows is the kernel source (and even that isn't that closed, start your reading here: http://technet.microsoft.com/en-us/sysinternals/bb963901).