The Simpsons was at it's best when they drew characters from separate franchises for small gags "on-model" rather than giving them that Matt Groening look where they are yellow and have no overbites.
As much as I rag on Disney, they used to have a sense of sincerity, not just them but children's animated movies in general. This of course ended when every company wanted to make the next Shrek writing wise so now we have stuff like "Influencer Smurf"
The Fallenchungus situation is like that “infamous” Skinner episode where the actual person was so boring and unlikable that people preferred the imposter more