Microsoft had tablets for a decade before the iPad came out. You rarely ever saw them in the wild. In fact, you still rarely see a Surface tablet. At least, I don't.
Many years later, I was working for a startup called kWhOURS in a little old house in East Cambridge, Massachusetts. Our target users were engineers used to paying thousands for the rugged and expensive Windows laptops we needed to deploy our Adobe AIR tablet app onto since they had a touchscreen. Still a clunky UI, but our software was usable. Then the iPad was released, and it was literally worlds apart, something people have long taken for granted. All of us, including Adobe, were taken by surprise, because all attempts at tablets prior to that were so far inferior to Apple's version, and competitors spent many years trying to catch up.
Tablet were pretty commonly used by delivery drivers and other employees of national corporations who came to my apartment building, but I don't know for sure that they ran Windows.
Oh yeah, that's been awesome for the consumer.
Apple tries extremely hard to be durably differentiated from products in the same category to avoid being dragged down in a price war to have cheap quality.
That in turn makes it hard for others to compete with them - you don't have differentiating features that would pull existing users off a mature product like iPad, and you can't come out with a cheaper product without discriminating consumers being concerned that it is fragile, clunky, and/or incomplete.
