I can't see a critic taking that dictionary definition very seriously. If you had looked at Wikipedia instead, you'd see no animated show is discussed in the article on sitcom, suggesting animated shows are considered a separate genre.
If you opened a textbook on mass media, it might have a definition of sitcom that is more culturally relevant.
From The Simpson Wikipedia page: "The Simpsons is an American adult animated sitcom created by Matt Groening for the Fox Broadcasting Company." The sentence links to the "Animated sitcom" page, which states, "An animated sitcom is a subgenre of the sitcom that is animated instead of live action that is geared toward adult audiences in most cases. South Park and The Simpsons are two of the longest running animated sitcoms."
If you opened a textbook on mass media, it might have a definition of sitcom that is more culturally relevant.