self section

Hello, there is something I don't understand about the "self" section. To me, it only applies when the person isn't playing a role or reciting a script, but is, for example, being interviewed or participating in a television game show.In the case of stand-up comedy, the performer recites a written text; he is an artist performing on stage, he plays a role even if he presents himself under his own name, as Ricky Gervais does in his shows. Why, then, are Ricky Gervais's shows classified under self section and not cast section?