Granted it isn't always the same one, Toei seems to treat Leomon as the throw away "the mentor must die for the main characters to grow and develop" trope.
In all good parody, you acknowledge a subject's strengths while playing toying with its flaws. I thought about how if the characters were actors instead of illustrations and if having to be killed off so many times caused Leomon to fall into a depression and ends up letting himself, that and I felt I needed some practice on generally fat bodies.
®Toei owns Digimon