Correct me if I'm wrong, but here is my take. Cable tv channels as we know now such as HBO who was one of the first in the late 1970's, decided, if you pay us you can have our channel commercial free. Other cable channels came along over the years and pretty much followed the same commercial free standard. 2 that come to my mind are MTV and Nickelodeon. I remember seeing MTV for the first time when I was about 6 and don't recall viewing ads. Over the years these cable networks 'evolved' and figured out they could double dip by showing advertisements constantly without too much uproar. We are at the point now were some channels will take 2 and a half hours to play a 1 hour and 20 minute movie. Personally I think this is a fraud, and partially weighed on my decision to cut the cord on satellite tv about a month ago.
I've also found this long forgotten gem. I love it when Satan comes to me in my nightmares.