I came across a similar article last year when I was researching my first grow. It was one of the reasons that I went LED. In that article the problem growers were having was that the ballast would interfere with theirs and their neighbor's cable TV reception. I am not very technical but evidently the neighbors would report problem and the cable company has the ability to figure out it is RF interference and triangulate it. Then the cable company, with a cop sitting in your drive way, knocks on your door and asks if you have any devices that could be causing a problem.
I don't think this is super prevalent but it does happen. I started looking for magnetic ballasts and ended up going LED but I am only growing a few plants and understand that HID are more cost effective in the larger grows. It is a sucky issue because it is hard to know if your ballast is a problem until after you purchase it.