I think it depends on the display driver installed. What is clear is that they err'd on the side of caution for a number of monitors "just in case", and that is merely conjecture. I have seen it before, but don't have it for my SyncMaster P2770 on this install. There is native driver support in Windows 8 for this monitor as well as a driver on Samsung's website. So what I'm saying is if they weren't sure, they may have just granted support for it. I know for a fact its not based on resolution, as some techs have suggested, because I'm in 1080P. Some have said if you have a high monitor resolution this appears, but I'm sure this is not the case.
Its probably based on the monitor driver and properties assigned to it. Most of these drivers are compatibility drivers from Microsoft like "Generic PnP Monitor", etc. They must assume that some time in the future, most people will have pen and touch support, and if not, they err on the side of caution.