Oddly enough, WDW does have other Disney Characters that exists with general visitors only seeing at extremely rare occasions. But are usually reserved for very special events held at the resort (notably exclusive to Cast Members and occasional Private Parties/Events). I remember stumbling upon photos to the other Lilo & Stitch characters (such as Jumba, Pleakley, and The Experiments) besides the titular duo from either Instagram or Flickr that was only held for Cast Members. Meanwhile, Clarice went from being a Rare Character at WDW to only appearing for events for Disney Vacation Club Members. At least Disneyland Resort had started utilizing her more in other events in recent years.i have pictures of me with chip and dale and little john from 83 somewhere. But the parks and crowds were so much different. Less crowded, no social media, no cell phone cameras.
But part of this is Disney worlds fault, all characters are locked away in meet and greets and you rarely see them roaming around. So when people do see them roaming around they freak out, I also dont think Disney World has nearly as many costumed characters available to them, so they arent able to "flood the parks" with them to make them more normal. Also different guest demographic.
Don't get me started with the Pinocchio Characters and The Seven Dwarfs being demoted to seasonal appearances over common meetable characters since the 2010s outside of parades and shows.