Everyone who joined the troupe post-Henson was a fan, and each got to impose their own new characters into the canon. Each writer hired for a new feature essentially got to take whatever they'd wanted to see the Muppets do and bring it to life. The retcon of Gonzo's origin in Muppets From Space was pretty well done, but it's the sort of hole that Henson would have happily left unfilled. Eventually, in It's a Very Merry Muppet Christmas Movie, we got the Alternate Universe With Cage-Dancing Scooter, which you must admit has that certain flavor about it.