A lot of it is the idea of "seinfeld isn't funny". Seinfeld was fairly revolutionary at the time because of how it approached humor, pacing, and even character "design". It is just that it also influenced almost every single show that came after season 3 or 4 so a lot of people who didn't "grow up with it" won't really "appreciate it". But that also manifests it as being the kind of show that "ages well". Its why TBS still shows Seinfled reruns to this day and people still go for a re-watch.
And Frasier is very much in that same category. Character arcs were very much ahead of their time and the nuance that Niles, Martin, and even Frasier were allowed to have still stands up today (and puts the reboot to shame). Its "cheating", but there is a reason that Cheers, which was arguably the most popular sitcom on television during its run, is now mostly viewed as the show Frasier spun out of. Its the kind of writing and pacing that largely could be on TV today... because it was so influential.
Friends is the odd one out. And I think, ignoring all of the "Wow everyone was horrible" and "Ross is a psychopath" memes: It very much defined what shows like How I Met Your Mother would become. I don't think it holds up anywhere near as well as Frasier, but that is also because Frasier largely ended a year after their shit season and had the payoff of Niles and Daphne's child. Friends... continued for another five or six with the main thread being "Oh, I guess we are doing a will they or won't they with Ross and Rachel again?"
Like, you reference The Good Place which I also put as one of the all time greats. And that, as well as Parks and Rec before it, very much benefited from shows like Frasier that show you can truly do the multi-season emotional arcs in a sitcom where you alternatingly laugh and cry. And Chidi has a LOT of Crane DNA in him as he is simultaneously mocked for being a "hoity toity, barely functioning, intellectual" while also having so much of the show's emotional and narrative weight put on his shoulders. We laugh as he has a nervous breakdown over having the future of everything put on him but we are also right there with him and rooting for him to find The Answer. He is a goober but, bah gawd, he is OUR goober and if he needs to make a big vat of chili to function then let's go to the mother fucking store.
Sometimes you have shows like Veronica Mars. It was SPECTACULAR for what it was but... not a lot of people are going to be arguing for newbies to really watch it. But it also laid a lot of the groundwork for shows like iZombie which... look, I love that show but I am also not going to really be encouraging people to watch it at this point. Whereas Jessica Jones has a LOT of the same DNA and... Season 1 of that is spectacular and holds up.
Whereas something like MASH is arguably the genesis of a lot of "very special episodes" that everyone hates. But it very much popularized the idea of "the sad clown" dealing with horrible stress and strain (which would be the basis of shows like ER and even House) as well as a willingness to "poke fun at" some truly important contemporary issues even while giving them the respect they deserve. Which was obviously important in the 70s (hmmm) but is also a direct ancestor of shows like Boston Legal and Brooklyn 99 (and even The Good Place) that aren't afraid to acknowledge things like systemic racism while also making us laugh because... the alternative is to just shut down. And while I don't hear as many people say "you should watch MASH in 2023", its best episodes are still held up as masterpieces.
And while I think All in the Family needs a lot more credit than it deserves, it was very much more of "a very special episode" rather than blending. And The Jeffersons (and the first season or so of Family Matters) is similarly incredibly influential but suffers from being "a black show". Whereas something like Fresh Prince of Bel-Air found a way to get that to a wider audience who won't clutch their pearls if they see Tyler Perry on screen.