Earlier quoted context omitted.
But what is a Windows 8 PC? Just because a PC is sold with Win8 (because prior versions aren't available) doesn't mean people are using it as such. They had to bring back "boot to desktop" as a configuration option, and 60% of win8 machines launch metro less than once a day ( https://www.soluto.com/reports ).
so case and point, metro is a pretty cool in function but lacks the apps to make it truly useful... So maybe the company trying to push it should make some. also you cited a link to a 404 page.... and additionally only someone not on windows 8 would believe a statistic like that its not possible to use many of the features of the OS without going into the metro interface... I am hoping that maybe your quote is that "…
However, most OS features do not trigger a new hosting process. For example, connecting to a Wi-Fi network, or opening the charms. (Control Panel would get detected as a Metro app, but how many people open Control Panel every day?)
So while it's not perfect, it is possible to make a first stab at measurement.