There actually is! I’m not sure if it’s at the same level as weebism in the west, but there’s a sizable fanbase for western animation in Japan. Lots of young people there have a fascination with western culture, and as a result a lot of them are big fans of American cartoons, especially Disney and recently shows like adventure time.I think there might legit an American cartoon fandom in Japan.
I know of at least one video about Japanese fans of King of the Hill arguing over subs vs. dubs.
It’s actually one of the main reasons shows like Lilo and Stitch and Power Puff Girls got their own animes in Japan, and pretty much the entire reason Kingdom Hearts got made.