Vales of keys in the left operand are overwritten by values of keys in the right operand.

Thats not obvious and breaks a commutative property. This observation about operators seemed poorly crafted to support a decision he already made. The existing example was unnecessarily complicated...most languages just do a singular function with a return val. Why be obtuse in the example? Preconceived agenda. The operator isnt compelling for dicts/hashmaps in any language.

Lots of operators are non-commutative. You can't "break" a commutative property that doesn't exist because the operator is not yet defined.

> You can't "break" a commutative property that doesn't exist because the operator is not yet defined.

That's the point (eg modulus). There's an entire preamble that's not relevant to the decision. The coverage of the inane "insights" is some hero worship hype.