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A. Neumaier said:Because there is something called the classical limit. Quantization is the converse - the inherently ambiguous approach to infer a smooth function of ##\hbar## from its limit ##\hbar\to 0##. One can always do it up to ambiguities of order ##O(\hbar)##, reflected in quantization by the operator ordering ambiguity. Thus there is no mystery at all.
Of course. It strongly suggests it - but as far as I can see, that's all:
https://arxiv.org/pdf/1201.0150.pdf
This is not about the well-known ordering issue - it is why the fundamental idea works. I have a sneaky suspicion QFT may have something to say on it - you can comment on that better than me. Some think QFT does not strictly imply QM:
https://arxiv.org/pdf/1712.06605.pdf
I also think the work of Gell-Mann and Hartle on a semi-classical limit provides even stronger evidence, but my understanding is that issues with it remain. I believe researchers will resolve them, but right now, the program looks incomplete.
Thanks
Bill