You comparing handheld to home console sales, are equally irrelevant, and it seems the only people who do this are Nintendo fans. Wonder why. Probably a combination of the Wii U's irrelevance month to month, and the PS Vita's irrelevance month to month. Whatever makes you happy, I guess.
No, NPD does this as well. There is a reason why When 3DS wins, the Home Console that gets 2nd overall says #1 for HC.
Also the same argument can be said about you or Non nintendo fans excluding 3ds, soooooo...... But hey watever floats your boat.