I understand that. I was responding directly to a comment from
@LangfordBarrow that mentioned finding a lost car or a lost gun you should be able to track down the owner.
Stolen firearms and straw purchases are related but separate issues. You can't necessarily address one and also address the other.
Manufacturers are required to keep a record of firearms they produce with their serial numbers now. They track them in their acquisition and disposition books when sold to a distributor and the distributor does the same when sold to an FFL. We have to keep our A&D book up-to-date with this same information when the firearm is transferred. The FBI traces the firearm using this information already during their investigations.
If an owner sells something privately that isn't against local or federal law they're already being responsible. I believe 20 states currently have a state law in place requiring all private sales to go through an FFL for the BGC and to document the sale.
People who buy several firearms but never seem to keep them can be a problem. That's what got the Malinowski dude in trouble. But not every one of them is buying and then selling to a felon or other prohibited possessor. I agree that habitual straw purchasers need to be addressed.
There are plenty of responsible gun owners who do more than our fair share of "taking responsibility". I don't know that there is much more we can do that will please those who seem to only want to implement more requirements and control.