Get rid of that poetry please and give me a single reason why PyCharm’s algorithm that infers types within the functions in Python should not work; but actually

Get rid of that poetry please and give me a single reason why PyCharm’s algorithm that infers types within the functions in Python should not work; but actually works reasonably well in practice. As a matter of fact all examples given in the papers you provide deal with generalised second-order cases of functions accepting functions which can be resolved by simply allowing to annotate said functions with the types by hand instead of inferring aforementioned types.