It happens on Macs I’m sure, but the picture in my head of someone doing this to the extreme is definitely a Windows user.

[edit] for my part, as a Mac user, I couldn’t tell you whether my desktop’s full of icons (probably not?) nor what my background image is (… the default? Which I’m guessing is probably a mountain or a wave or something?) because I see my desktop so rarely, and never pay any attention to it.