This hits the nail on the head. People don't want an objective answer, they want the reason they can't have what they want (a decision, a win, a tight call) to be somebody's fault.
Even with increased consistency, we need referees because interpretation of the laws is often subjective, so someone has to do it. In more complex cases, like this, even where the decision is ultimately objective (ie. the law says you're offside in this case), players, managers and spectators still feel the answer itself is subjective and therefore arguable.