Societies need up to date information, even to dismantle Big Government.
So what doesn’t the “Commerce Clause” allow?
To be quite clear the census clause does not require it. And the Fourth Amendment’s “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated” is quite strong in suggestion that the Federal Government has no permit for asking such intrusive questions.