I don't have any first hand experience, but I've heard that the signal going down the line was actually 3.7-4.2 GHz. So it had to be very 'low loss' feed line.
I think it was probably because when Satcom K1 and K2 were launched around 1983 or 84, NBC was still owned by RCA, that also owned RCA Satcom. If I remember right back around '85-'86 RCA and HBO tried to get cable headends to convert to the Ku-Band. They offered free Ku earthstations to cable operators. HBO and Cinemax E & W were on K1 or K2, and HBO's short lived "Festival" family oriented movie service was Ku only in addition to being unavailable to TVRO.