Cable just carried regular broadcast channels back then. The value you paid for was more channels and better picture, not avoiding ads. HBO was the first premium add-on, and it didn't have ads.
Some people set up a big dish antenna in their yard so they could get content directly off the satellite backhaul. This might not have had ads but it was a fairly big investment and you had to be sort of an AV geek to use it.
The cable provider was just a delivery mechanism. So you pay them to deliver the feeds. But they didn’t get any revenue from the content providers (or their ads).
In other words, two different companies, two different services (content vs delivery), and two different revenue models.