These are only the ways of closing a Window that I know of. I'm sure that there are more. But that is still a way for them to adjust to a bad interface. The problem is that most people accept the idiocy of interface, and loss of productivity, without blaming Microsoft. And humans are amazingly good at adaptation, which is why windows doesn't seem as bad an interface as it really is.
Some people naively think more is better.
You aren't forced to use those other ways. Remember that most ways to close windows are fairly complex, with multiple steps, so people don't use them. If people do use those ways, then they reduce their productivity. Imagine you are a new user, and you ask four different people to explain how to close a window. Imagine you are unsure of yourself, all those choices are confusing and overwhelming.