WMG / Space Stars

The reason the Cartoon Network and Boomerang never showed it in its entirety is because...

They likely couldn't find versions of the episodes that didn't have Casey Kasem's narration ("We now return to our program.")^note At the time it originally aired, Casey Kasem was a staff announcer for NBC who was usually heard on Saturday mornings, usually doing the Ad Bumpers, and announcing the return of the show on the episode title cards (which is otherwise done on a separate ad bumper), similar to what ABC usually does., which was likely also the reason the USA Network showed most of the episodes without their episode title cards.