[lemagedurage]

Since Python 3.7 preservering insertion-order is part of the language specification.

"the insertion-order preservation nature of dict objects has been declared to be an official part of the Python language spec."

https://docs.python.org/3/whatsnew/3.7.html

[nerdponx]

Right, but that's kind of my point. Adding it to the language spec now creates an additional and frankly somewhat unnecessary point of compliance for other implementations. Python is already so damn big and complicated, my opinion is that we shouldn't makes its spec even more complicated, even if its reference implementation adds more features like this.