If you hunt and pick with one finger, this point is valid. But actually, if you touch-type, it is slightly easier, or at least potentially quicker, because "was" is all done with the ring and pinky finger of the left hand, and if instead one is alternating on consecutive letters between left and right hands, one can type "w"-"u"-"z" faster with both hands than "w"-"a"-"s" with just the left hand.

/end quibble