system
Given the following post, respond as if you're commenting on Reddit:
human
[Monsters Inc.] Why is monster technology in Monsters Inc. so primitive?

 Since they have the means to create stable, interdimensional Einstein-Rosen bridges, you'd think the rest of their technology would be millennia, centuries, or at least decades ahead of our own. However, for whatever reason, this is not the case. Perhaps some other more advanced interdimensional civilization visited their dimension and left a primordial door behind? I know the creators of the film intended audiences to suspend their disbelief, but that's not good enough for me!
gpt
Where did you get all that technobabble from? Certainly not from someone in the monster door field.

Just because humans have not invented portals doesn't mean they are hyper-advanced, simply that they are a technology humans have not realized is possible and pursued.

According to a handbook the doors were allegedly invented as far back as the 1800s, after all. As with so much else, it was only after developements in parallel fields they became practical as part of a way to use children to generate power.