Way back in the day when I was in an elevator and I heard the "Muzak" play a Beatles cover, I always thought to myself, this is nice but I would rather actually listen to the Beatles.AC began in the early 70's, while Beautiful Music lasted well into the 80's. But AC, first known as "chicken rock", was pretty much the more adult songs from Top 40 and initially was a 25-44 target. As time went on, the Beautiful Music 35-54 listeners became 50+, and AC became 18-49 and the sales demos for instrumental fans aged out.
But, more than that, the sources of music dried up. Record labels could not sell anything except a bit of Pourcel and Muriat, and many of the orchestra leaders and arrangers died. And the current hits of the later 80's did not make for good covers... an instrumental of "YMCA" was not very appealing.
Occasionally, I would hear an older adult (my parents age) humming along with a familiar Beatles or other contemporay artist's tune and I would ask them if they new who wrote it it. They would be amazed at the answer because they would say that they didn't like the Beatles or other such group.