Because most business owners don't want to go to the expense of hiring a dedicated IT guy to manage a bunch of computers that their staff don't know how to operate.
Most businesses already have a "dedicated IT guy to manage a bunch of computers that their staff don't know how to operate."
And the computers are Windows!
People have been using windows for 40 years and most still are not good at it.
That will never change.
The cure? Believe it or not