Of course it matters. Just think how absurd it would be to ask a cattle rancher if every head of cattle matters, or a baker if every cupcake matters, or a fisherman if every lobster matters, or a bricklayer if every brick matters. Because it's all still "so new", online business has been tolerating a great deal of fuzziness that would be considered madness in almost every other kind of business. Clicks and impressions are a webmaster's basic inventory. Be concerned about accuracy and precision. Demand the same commitment from those with whom you do business. There is no gray area. It hurts us if we allow there to be.