Corky Marlowe said:
All in the Family should have stopped after the sixth season
The beginning of the end for that show may have been when Nixon resigned.
Once Jimmy Carter got elected, they tried a little role reversal, with Meathead defending the President and Archie railing against him.
Once they saw that that wouldn't fly (Stivic's character is a "smartest guy in the room" contrarian, not a defender of the establishment), they toned down the political bickering, and focused more on Archie buying the bar and Stephanie coming in.