The point here is that all western instruments have been set to equal temperament for at least 200 years (very approximately
). That's the system we work with.
Technically (in "pure" terms) every note is "out of tune" (except octaves), but it's the only temperament that allows our functional harmony system (keys, chords, modulations, etc) to work. We need all 12 semitones to be equal so that all keys are equivalent and we can modulate freely without retuning. We put up with the impurities.
It's true that instruments capable of sliding pitches (violins etc, the human voice) can perform in pure temperaments if they want - adjusting intonation for different keys. Unaccompanied choirs, for example, can sing (quite naturally) in pure intonation by ear. Most wind instruments can adjust their intonation too. (In fact, some wind players need to use certain lip or finger techniques to play exactly in ET anyway.)
But if they play with fixed pitch instruments like pianos, organs or guitars, then they will either be out of tune. or will need to tune to the ET instruments.
IOW, the point you are (were) making is not wrong, in theory, it's just not applicable in practice. (which is what the others were saying.)
In any case, IMO, the whole mathematical argument is a red herring. Who cares how many permutations there are? Musicians don't...