yeah I figured. I assume that it gives the actors something to do while others are talking.
especially if the scene has other people entering or exiting the apartment. like. George will eat an apple while jerry and Kramer are talking, since George will have something to say before, and after Kramer enters the apartment.
I dunno there's gotta be something to it. Many other sitcoms have multiple people involved with a scene that aren't eating all the time. I swear there's something going on. lol