This is the equal-temperament tuning, which is used a lot now because it's simple and consistent. Other tunings were common in the past, where they'd set notes to simple fractions of other notes like 3/2 of the note 5 below, idk the actual numbers they used. 3/2 isn't any power of the 12th root of 2 so nothing in this new system is actually as harmonic as it should be, but nothing is particularly dissonant either and the system is simple.