Whilst I can see your point, if there aren't any standards, then there's no reason why anyone shouldn't be able to just advertise as a 2ms all the time then, and not lose out to the "ignorant" market.
12ms is NOT fast enough that the eye can notice any difference, that part is a load of rubbish.
Unfortunately when we're buying online, we don't get the advantage of seeing two monitors next to each other and therefore base our decisions on other customer reviews who've taken the plunge.