The purpose is to ensure that the guns are in the possession of the registered owner, and not sold illegally; to ensure that the gun is being stored in a safe manner that will not lead to its theft or accidentally use; and so that the government can call upon lawful gun owners to defend their country in time of need.
There really has been no tradition of forced weapon confiscation in this country, and I think your insinuation to the contrary is born of paranoia.
Multiple elected officials have said they want to start such a tradition, e.g., Mark Warner (https://www.pbs.org/newshour/politics/what-action-should-be-...), Beto O'Rourke, Kamala Harris, and Cory Booker (https://www.cnn.com/2019/09/12/politics/beto-orourke-guns-de...). How is it paranoia to think they'll do exactly what they said they want to do?