Stern was very good to great, say 89-2012. Pre 89ish, it sounded like a hard morning zoo type show. 1989/90-2001 was great. Stern was young, had a fire in his gut, etc.... 2002 - 2008 were still pretty good. Then Artie got too hooked on heroin/coke, and Stern was left without a real comedian. There was a little spark left after 2008 that could make for interesting shows, but the fade started then.
By 1990, he also had a great support staff and back house crew. Stern, by himself, isn't super funny in a comedic sense, but he's a great director. He knows / knew when to push things and when to back off. The secondary crew, guys like Jackie, The Jokeman, Anthony Cumia, Billy West, Artie tend to get stuck on things that amuse them or make their friends laugh. That's why they can't host consistently.
The back house crew (interns, younger writers, etc....) is super important to these shock jock type shows too. After a certain point, the host(s) get old, too moneyed, settle down with family, etc.... So you don't hear the gossip, infighting, partying stories that really make these shows great, that's why you need those younger people.
Howard and crew were also good at spotting retards and other odd people to add filler content to shows. Probably the best show to ever do that type of thing.
Fast forward to around 2012, and that's when you really see the collapse. "Hollywood Howard" kicks in. He wants to be accepted as a serious journalist, so anything not p.c. starts to go away. Old tapes are edited for racial humor, etc.... His wife (20+ years younger) also wants the jetsetter celebrity party lifestyle, so he isn't mean to them anymore.
There's also a money protection angle to all of it too. Stern and his agent have always been spotting trends, so the nudity, meanness to fat women, racial groups, etc.... ends before MeToo, etc... become a thing. Any of the edgy writers were shelved, or forced to go gayer, lib, etc.... during this time too.
Also, you can't be mean when your daughter puts out stuff like this -
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Anyway, those are my Stern ramblings, from a person that listened to a lot of talk radio growing up.