Meh. I think that's sort of overstating things. Pythagorean tuning is an iterated, circle of fifths construction of a scale. And as such it... frankly kinda sucks rocks at explaining triad-based harmony. The numbers don't work out. You can get something that kinda sounds like a chord, but not really. And so two millenia of Pythagorean music really didn't get into triadic harmony at all, because the language that it had with which to express those notes didn't permit them.
It wasn't until vocal music in the early enlightenment essentially happened upon major/minor chords and built modalities around them (largely by accident, because they sound good!) that people went back to the drawing board to build a mathematical description of the scale based on integer ratios instead. And from there, it was a quick jump to the equitempered scale we know today, which (unlike the pythagorean scale) actually is a very good approximation to the "real" chords people were singing.
And the first composer to really put all those new tools together into a coherent theory behind how to compose music was... J. S. Bach. He didn't "invent" all that stuff, but his works were the first ones we can look at and recognize what we now call "modern" exploitations of tuning and tonality. Anyone earlier was missing big pieces. Anyone later was only adding something new here or there.
JSB is a genuine discontinuity, and it's worthwhile to celebrate that.
It wasn't until vocal music in the early enlightenment essentially happened upon major/minor chords and built modalities around them (largely by accident, because they sound good!) that people went back to the drawing board to build a mathematical description of the scale based on integer ratios instead. And from there, it was a quick jump to the equitempered scale we know today, which (unlike the pythagorean scale) actually is a very good approximation to the "real" chords people were singing.
And the first composer to really put all those new tools together into a coherent theory behind how to compose music was... J. S. Bach. He didn't "invent" all that stuff, but his works were the first ones we can look at and recognize what we now call "modern" exploitations of tuning and tonality. Anyone earlier was missing big pieces. Anyone later was only adding something new here or there.
JSB is a genuine discontinuity, and it's worthwhile to celebrate that.