Can someone at Pixar confirm or deny this? Pees?
They base their assumption on the fact that movies contain models from other movies, when those are merely Easter eggs. It's like saying MSFT wanted to turn accountants into pilots for 9/11 by including a flight simulator into it. It breaks down under scrutiny.
It's a wonderful example of how, given a sufficiently large dataset,
one can cherry-pick what one needs to construct almost any narrative.
My daughter broke the time line, though, by pointing out
that Heimlich has a cameo in Toy Story 2. I do want to
give the author props for inventing the idea of the
Monsters Inc. doors being time portals. It doesn't really
work, but it's witty.
As in the case of Andy's father the real reason Pixar
films contain references to other Pixar films is rather
mundane. It's only because somebody thought it would be
funny and the director agreed. In the cases of things like
John Ratzenberger's voice and the Pizza Planet Truck,
it's tradition and a challenge.