I agree that the lack of competition had a lot to do with it. I think that even in the late-1960s, ABC was not treated as an "equal" to NBC and CBS as far as networks go. In the chart shown in Post # 75, almost all the "Bottom" rated shows were ABC series. This is similar to how the Fox Network looked in the first ten or so years of its existence---a few hits but many, many more losers that filled up the "bottom rated" lists.
.
Fred Silverman to the rescue for ABC:
"Silverman was named president of ABC Entertainment in 1975,
[10] putting him in the ironic position of saving
Happy Days, the very show that
Good Times had brought to the brink of cancellation. Silverman succeeded in bringing
Happy Days to the top of the ratings and generating a hit spin-off from that show,
Laverne & Shirley (another spin-off,
Mork & Mindy, was also a ratings winner initially ending its first season at number three but the ratings quickly free fell).
At ABC, Silverman also
greenlit other popular series such as
The Bionic Woman (a
Six Million Dollar Man spin-off),
Family,
Charlie's Angels,
Donny & Marie,
Three's Company,
Eight Is Enough,
The Love Boat,
Soap,
Fantasy Island,
Good Morning America, long-form pioneer
Rich Man, Poor Man, and the award-winning miniseries,
Roots. These moves brought ABC's long-dormant ratings from third place to first place. However, Silverman was criticized during this period for relying heavily on escapist fare (it was Silverman who conceived the infamous
The Brady Bunch Hour with
Sid and Marty Krofft in late 1976) and for bringing T&A or "
jiggle TV" to the small screen with numerous ABC shows featuring buxom, attractive, and often scantily-clad young women (such as the popular
Battle of the Network Stars).
ABC Daytime had mediocre ratings, so in order to increase them, Silverman hired
Gloria Monty to produce the ailing
General Hospital. He gave Monty thirteen weeks to increase the serial's ratings or it would be cancelled. He later expanded
General Hospital,
All My Children, and
One Life to Live to a full hour, and created a 3+1⁄2-hour afternoon serial block. Among game shows, Silverman introduced Goodson and Todman's
Family Feud to the network."
en.wikipedia.org