What is Gun Registration Useful For?

A fanatic gun control advocate* on Huffpo claimed :

To control gun violence in our nation: Registrati­on and reporting of private sales is the only way the illegal traffic can be controlled­. All other efforts are counterpro­ductive.

Well most of us know about the case US v Haynes which states:

We hold that a proper claim of the constitutional privilege against self-incrimination provides a full defense to prosecutions either for failure to register a firearm under sec.5841 or for possession of an unregistered firearm under sec.5851.

Huh? What's that? A felon can't be prosecuted for not registering but your average citizen can?

Well after some non-felons got convicted for not registering, Congress made a tweek to the USC so that NOBODY can be convicted for registering:

(a) General rule No information or evidence obtained from an application, registration, or records required to be submitted or retained by a natural person in order to comply with any provision of this chapter or regulations issued thereunder, shall, except as provided in subsection (b) of this section, be used, directly or indirectly, as evidence against that person in a criminal proceeding with respect to a violation of law occurring prior to or concurrently with the filing of the application or registration, or the compiling of the records containing the information or evidence.

LA showed this in State v Hamlin:

The 1976 amendment to La.R.S. 40:1784 was obviously enacted
for the same reason as 26 U.S.C. section 5848, namely, to
constitutionalize the firearms registration requirement of La.R.S.
40:1785 against claims that that statute violated the
constitutional privilege against self-incrimination. Thus, for the
reasons articulated by the United States Supreme Court in United
States v. Freed, supra, we hold that La.R.S. 40:1785 does not
violate the privilege against selfincrimination as guaranteed by
either the fifth amendment of the federal constitution or art. 1,
section 16 of the Louisiana constitution.

Now registration information can't be used to prosecute someone who is a prohibited person. So what is the point of registration? The same as it's always been:

The City of New York's Gun Control Law is not aimed at
persons inherently suspect of criminal activities. It is regulatory
in nature.

Citizen control. Not crime control. That is the point of registration.

*H/T to Clayton Cramers article available here.

*Honestly, she thinks the NRA bought off the FBI to skew crime statistics.