People who were camping, or in some other environment where watching TV wasn’t practical, could also listen to the news, or their soap operas, or whatever. The extreme left end of the FM dial often has TV broadcasts as well.
Yes, when I got cable around 1984, in my area it involved a splitter.
My TV had screw terminals for a VHF antenna, and my stereo receiver basically had the same type of terminals for AM and FM antennas. A cheap radio antenna consisted of a 6 foot piece of speaker wire split down most of its length.
So the main cable came into the splitter and then one output cable with clips ran to the TV and one ran to the receiver.
MTV was the only TV channel they fed to the receiver in my area, but they also fed local FM stations and a couple of out-of-market ones.