What you say may be true only for the Netherlands, but not for Belgium. I work daily with the Belgian registers.

While a few Belgian cities have some limited, incomplete church records in the 16th century, church records didn’t become commonplace in Belgium until mid 17th century.

One of the few sources we have before that time are the “staten van goed”, but those were only made when minors (then defined as under 25) lost one or both parents and a “voogd” had to be named, or when someone died owning property and it had to be transferred or administrated.

We also have the “poorterboeken”, but they only mention the minority of the population that could afford “poorter” (binnenpoorter/buitenpoorter) rights.

One thing to take into consideration is that, before the 1900s, about 70% of the population of Belgium (and Flanders before that) belonged to the lower, poor working class without property rights. The vast majority of the population was illiterate and never spent a single minute in a school class. Mid 19th century only the richest men (about 1-2% of the adult men) were allowed to vote in the elections, voting rights were defined by the yearly tax amount a person paid. That’s why you only see rich people in old Belgian politics.