>the reason we have the atf is because of mobsters like al capone
And mobsters, like Al Capone, came into money/power BECAUSE OF the Prohibition. And indeed, the ATF was created to employ all the federal agents that were no-longer needed to enforce the Prohibition laws.
In other words, government created a contra-Constitutional agency to employ people who no longer had Constitutional authority... so, again, by what justification does the ATF exist?
nixon while president separated it from the jurisdiction of the irs
they enforce tax law for alcohol and tobacco. they enforce that firearms are being sold according to federal law