In older versions of Windows 8, swiping up was indeed necessary. And, in fact, there was an affordance (of sorts) to let you know that that was what you were supposed to do: if you did anything that was not a swipe-up, the screen bounced up slightly, revealing a little bit of the login screen underneath. After seeing that, it was a little more obvious what to do.

Now, obviously that was still a pain in the ass and Microsoft wisely axed that requirement for mouse-based computers. Now I think things are much better -- yes, there is no affordance telling you what to do, but if you do literally _anything_, then you get what you wanted. That's not too bad.