Rather than quibbling over when the golden age officially ended, I’d be far, far more interested in the ratings of later episodes that are actually good so I don’t have to slog through all the garbage. [Related: why are none of season 1-10 episodes ever in the re-run broadcasts?]
Crowdsourcing the end seems valid, but the guy who hit upon The Principal and the Pauper as the end (an episode that I like, FWIW) has a really good reason: The core writing staff all left. You can analyze it from crowdsourcing or you can analyze the staff but the results overlap around the same general time.
When you get into the post Season 9 twilight of the show, not only are there only a few people left from the original staff, there are only a few people left from the original replacements. By Season 12, the only writers left from the Mirkin era were Scully and Mirkin themselves. Even the Oakley and Weinstein hires from Seasons 7 and 8 had only two writers remaining by Season 12, Ian Maxtone-Graham and Ron Hauge.
That the writing staff was able to be successfully restocked once was a small miracle; it simply couldn’t happen a second time. Those changes, combined with the general exhaustion of having told so many stories about the same characters already, was probably more than any show could have withstood. But the show’s fate was permanently sealed when it lost two vital staff members, Doris Grau and Phil Hartman.
we miss you, Mr. Hartman.
