Although cable television was never conceived of as television without commercial interruption, there has been a widespread impression - among the public, at least -that cable would be supported largely by viewers’ monthly subscription fees.
The premium services mentioned in your quote (HBO, Showtime) also still do not run ads even today.
Literally the first sentence of that article:
The premium services mentioned in your quote (HBO, Showtime) also still do not run ads even today.