In 2012, the FTC put on their Robocall Summit. It was livestreamed, so I watched it. One thing I took from it was that there were many smart and dedicated people at the FTC, but that it was a hard problem.
One thing they didn't say, but I suspect is true, is that the FTC is not well supported by Congress. Look at how hard it was to ban telemarketing in the first place. Look at how energetically the CFPB is being undermined.
Dedicated people aren't enough. You need institutional support, including money, resources, and laws that actually let you put the criminals in jail.