I have heard or read quite a few times that CBS executives literally didn’t like rural shows.
I think they probably had pretty much run their course tho ratings were still good.
The thought was the rural comedies didn’t play well in urban and suburban areas, where audiences were more affluent. So, CBS cancelled all of those shows on a single day in 1971. “They cancelled everything with a tree,” observed Pat Buttram, who played Mr. Haney on “Green Acres,” “even Lassie.”
The mass cancellation opened the door for “edgier” shows, such as “All in the Family,” “Maude,” “Mary Tyler Moore,” and the “Bob Newhart Show.” Some became classics, but it’s funny: you can still find “The Beverly Hillbillies” and the other rural shows on Antenna TV and other outlets, but the topical comedies largely bombed in syndication and it’s hard to find them on the nostalgia TV channels. What was timely and hip 50 years ago is tired and unfunny today.