Are HomePlug adapters really that large a source in practice, though? I'm an amateur operator and I've spent no small amount of time messing with HomePlug adapters and various bits of equipment to measure interference. Yes, they do produce very broad noise when the network is in use (although mine, and the internet suggests many others, intentionally filter output near amateur and other in-use HF bands).

That said, I think that these devices are actually quite rare in the real world - most people don't even seem to know what they are - and in my testing the noise dissipates very quickly as I leave my house, disappearing into the background of the city after only 20-30 feet.

I think that regulators have definitely dropped the ball on HomePlug, but I also don't think that it's that much of a problem, particularly given that it's been a commercial failure. Most of the ire towards HomePlug comes from people being upset about commercial-scale BPL installations, which actually have the potential to be a major problem over a large area.

In my house, my monitors actually account for more problems I experience than the HomePlug adapters do, in my everyday radio usage. And they aren't even cheap knockoffs, they're pricey name-brand models.