The Nazis didn't actually need the pre-occupation data from the civil registry to easily find Jewish people.

In January of 1941, the Nazis ordered all Jews in the Netherlands to register themselves and virtually all of them, some 160,000, provided their name, address and information on any Jewish grandparents to the government.

If the lesson one learns from the Holocaust is that one shouldn't collect data just in case some genocidal group comes to power, then I fear one has learned the wrong lesson.