Quantum contextuality, as demonstrated by the Kochen-Specker theorem, proves that measurement outcomes in quantum mechanics cannot be explained by non-contextual hidden variable theories.
The retrieved literature (such as papers 2, 3, and 8) explicitly discusses how the Kochen-Specker theorem and quantum contextuality rule out non-contextual hidden variable models where measurement outcomes are assigned pre-existing non-contextual values. Therefore, the claim is strongly supported by foundational results in quantum mechanics.