As an amateur radio operator, LEDs have been the absolute bane of my (and thousands of other city-based hams') receiver. Those same modules not only produce ungodly amounts of heat, but also loads of radio-frequency interference that has been contributing to the increase of the global HF noise floor over the last decade.
I think jandrese is referring to the fact that even a DC current through a plasma generates loads of RF, for example fluorescent tubes emit THz radiation!
And it's not only hams, but also other radio spectrum users, like mariners -http://www.professionalmariner.com/December-January-2019/Onb...