I don't think the point was to discourage updates, but simply to flag them. There is no reason not to allow some updates, its specific types of updates that are harmful. With a last update stamp you would at least know that content had been updated, unlike now where you have to guess (which gets increasingly more difficult if you haven't looked at the specific node recently.)

Additionaly it would appear that the database already holds an update date, so then its merely a matter of adding it to the output.