The main characters are blatantly cribbed from the Simpsons and the cutaway gags that the show is famous for have absolutely no context - they can be used interchangeably in any episode.
Each episode consists of about 3 minutes of plot and 19 minutes of filler: almost anything the writers scribble down goes straight to air and 80-90% of it misses. If they have too many cutaway gags to fit into the allotted time, they just cut-and-paste them into the next episode because they have no specific narrative value.
Parker and Stone are, of course, not offended by any of MacFarland's content. Their beef is that his show exhibits total laziness, no craftsmanship and no regard for the audience - they're offended as writers and as consumers.