OK, so bottom line.
The feds do not keep records on all of our purchases.
But by requiring the dealer to keep his records forever, the information is there for the feds any time they want it.
The feds are getting what they want through the back door, thus avoiding the restrictions congress put on them.
You are correct.
I never really thought it through.
Seems like the FFL’s might have to start having mysterious break-ins and wastebasket fires...