I'd say it has to do more with the absolutely tiny process feature sizes, where transistors stop behaving like switches and the statistical uncertainties of quantum mechanics start becoming relevant.

14 nm is still a fairly large size on the molecular scale. Things of this size still behave classically for the most part (that is, ignoring the fact that a transistor, however large, is an essentially quantum-mechanical device to begin with). What might matter at this scale is thermal and capacitance effects.