Of course the Surface Pro/RT competes with the iPad.
I often read comments that the Surface doesn't compete with the iPad and should rather be compared to ultrabooks. Sure, the Surface Pro is a fully fledged touch-screen Windows PC but it was a reaction from Microsoft to Apple's ever increasing sales of iPads and a decline of PC sales.
So what does the Surface Pro need to be compared? To everything and nothing. It is competing with tablets and ultrabooks.
[Update:] All your comments are valid points. The Surface is still a reaction to the popularity of the iPad, its apps and its dominant sales. Both the Surface RT and Pro try to take up on that development of mobile, simple, light-weight touch-computing. Windows 8 (Pro/RT) tries to leverage on its base of Windows users to compete with the popularity of iOS.