In the earliest days of getting people to pay for cable TV when OTA was free, the pitch was that you'd see fewer/no commercials. That didn't last long...
No, it was quality of reception, especially for people who were farther from (or had inconvenient terrain between them and) broadcast stations; literally the only thing on early capable was exactly the normal broadcast feed from the covered stations, which naturally included all the normal ads.
Premium add-on channels that charged on top of cable, of which I think HBO was the first, had being ad free among their selling points, but that was never part of the basic cable deal.
HBO was the first offering that didn't have ads during the show.