That might be so, however its amazing what you learn by playing around with a small loop in your house. Things like wireless modem routers generate wide band hash. In some places they installed in the attic or a utility box for use with optic fibre. WHen you unsure where the noise is coming the loop can make pinpointing the source a very easy task. Its my No1 tool for finding noisy items without turning off the power.
Outdoors I have used the loop to identify a corroded and noisy LED garden light. The particular neighbor had 60 of these installed. With the loop I could find the exact faulty lamp.
I use my KX3 with this loop and it makes a excellent EMI finding tool.
There's no need to DF devices in your own home. Simply power OFF devices while monitoring the RF noise at the amateur station.