It's hard to believe in more ways than one, but in 1975 the FCC established Family Viewing Hour, which reserved prime time before 9pm for "family-friendly" television. A Federal Court abolished Family Viewing Hour in time for the Fall 1977 season, but by then the provocative comedy All in the Family had been moved from its very comfortable roost at 8pm on Saturday. This was before video recording became a popular phenomenon, so the schedule shift probably mattered more than it would today.
Here's a great clip of the All in the Family cast responding to Family Viewing Hour with a parody of the show's theme song. Jean Stapleton and Carroll O'Connor are at the piano, backed by Sally Struthers and Rob Reiner.
Thanks to Frank Santopadre for the lead!