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That YMMV page is only attached to the Goanimate platform page because the tropes which apply to Caillou videos are listed there, which itself doesn't seem right at all. On any other Platform page, the tropes list is only for the platform itself, not the works present on it or created with it.
Caillou Gets Grounded should be it's own work page, and the related subpages should be renamed to link to it.
But if I wanted to add a YMMV or Nightmare Fuel page to Microsoft Windows? There's a Memes page for it. There used to be a YMMV page for it at one point before it was deleted due to Windows being classified as Useful Notes prior to being changed to a Platform.
Common question: What is the difference between reality and fiction? There's a whole folder dedicated to Nightmare Fuel in computers on Other Media. Also, let's address the elephant in the room: Vanity Plate
Platforms, Useful Notes, Media Notes, and other articles about real things and/or people may never have YMMV or related examples. No exceptions.
The only exception is for Creator articles, which may have YMMV subpages about their work if and only if the specific works being discussed don't have their own wiki articles.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

There is a YMMV page for GoAnimate, which is classified as a Platform by TV Tropes, but they're mostly for those infamous videos where Kay-loo gets grounded grounded grounded grounded grounded for god knows how long. I think I just answered my own question but I could be wrong.