So I gave a reason why win 8 has it and wp8 doesn't.
Irrelevant. It's obviously a gesture for touch enabled devices. Windows Phone 8, a touch enabled device, doesn't utilize it while Windows 8 on a PC, a non-touch enable "device" does.
Are you just ignoring the evidence presented? Or are you simply not reading it?
As already mentioned *several* times. Windows targets a different hardware ecosystem from WindowsPhone8. Do you not understand how that difference can affect the *software* decisions in the OS? If the PC hardware ecosystem guaranteed the same things as the phone ecosystem, then Windows could make the same choices as WinPhone8. As the hardware ecosystems are different, the software is different. There is no irony here.
If you can't see the irony in this then you're either ignorant or naive.
Or, alternatively, because there's is no irony once you actually consider the facts of the situation:
I have a feeling you're using irony in an improper fashion as no definition for irony actually fits this situation. Indeed, i can't think of a single definition of irony that would fit the situation of:
1) A OS designed for general purpose PC hardware works differently than a phone OS designed for specific mobile hardware.
2) despite both supporting touch gestures, the set of gestures if not the same across both.
Indeed, if this is ironic, then frigging Apple is ironic as their touch gestures in their desktop OS don't match those in the mobile OS.
You seem to think it's the case that if two things are touch enabled, that they should share all the same touch gestures. There is nothing that dictates that that should be hte case, and it's not at all ironic when they don't.