I absolutely fucking despise Kyle with all my heart and soul. Trey and Matt just use Kyle to forcefeed shitty beliefs and "life lessons" into the show like the ending of a kindergarden book. Annoying, preachy hypocritical piece of shit that pisses me off
i am an OG south park fan, I've seen seasons 1-15 a few times, I've watched since I was a little kid and I can concretely say that there are a few main episodes that stand out clearly to me for the show's decline in comedy.
Season 5, Episode 13: Kenny Dies
Season 10, Episode 1: The Return of Chef
Season 12, Episode 4: Canada on Strike
"Canada on Strike" is easy to explain. It's the episode where the Numa Numa Guy and Damatic Chipmunk are featured. In 2008, at this time, Internet memes were going mainstream and it was a novelty. It's sometime after Season 9 but definitely by Season 12 where South Park is infected by Simpsons disease. Specifically, the show becomes what it was a parody of. The Simpsons was a counter-culture parody of saccharine family values sitcoms, only to become a hub of celebrity guest appearances. South Park parodized pop culture and politics, only to become a staple of pop culture and politics.
Kenny's perma-death through Season 6 and his subsequent deliberate sidelining in all future episodes really cost the show something and what's weird is I am both 100% sure of this and 0% certain of why. I think it may be that Kenny's death was often a device used to launch the plot. My all-time favorite episode remains Season 1's Halloween episode, Pinkeye, which I still think holds up and is awesome. Kenny's character was unique, reflected poor Americans, and also raised stakes by getting shit happening.
Pinkeye also heavily featured Chef. Chef's departure was a legitimately tragic loss for the show. Chef was funny, his songs gave the theatre fags writing the show a chance to add music to episodes, and he also routinely served as the voice of reason. That was often the dynamic for a lot of the early episodes. Kenny fucking dies, there's serious stakes, the boys are vulnerable and need help, but their parents are hopelessly caught up in whatever pop culture thing is being criticized, leading them to consult in Chef, who would sing a song and set them on their way, leading to the conclusion where the Jew talks about whatever. That's the show. I don't blame them for letting Chef leave, but I do think that they needed another Chef.
The vacuum left by Kenny's
je ne sais quoi and Chef's adult-in-the-room never got filled. The parents of the kids also slowly turned into parodies of themselves (Randy is basically just South Park's Homer Simpson). The children end up being their own saviors, which is lame, because the children are sit-ins for their creators.
Also since I'm on this tangent, the suicide of the original girl that played Wendy seemed to hurt the show a lot. Stan really liked her and there was romantic entanglements with her and it was a part of what made the kids feel more like kids and less like the creator's gay mary sues. They never believably act like children and so there's really no reason for them to be children. They might as well just relaunch the show as South Park 2025 and start the episode with literal depictions of Matt and Trey smoking pot together with that black wife of his.
I think that's basically it. Stan and Kyle are just Matt and Trey and over time they became less vague representations of them and more direct stand-ins. All the other characters lost their value because their personalities were concentrated too much in the two main children. All other characters merely exist to represent the thing being made fun of.
