Given history, you're wrong in that regard. SIGINT is something that doesn't get you nukes or get you to infiltrate MI5 to the point that you've got at least a person near the top and feeding you immense amounts of information about what they're doing to your other spy rings or literally run rings around the internal intelligence services while 'you can't touch this' goes on in the background (all of which the NKVD and KGB did in the Cold War). HUMINT does.
SIGINT is intercepting communications, and if you want to do more than getting radio signals, you'll need HUMINT to get in and build the rings, setup the taps, find the right people, etc.