Frankly, familiarity is a vastly more important aspect of music than any micro-tonal artist would like to admit. And while the overtone series is (in many many ways) the root of all music, not every overtone is equal.
For instance: 9/8 (a major second) is just (3 * 3)/(2 * 2 *2) and is generally more consonant (like dull, boring, unmoving: an octave or perfect fifth) than anything with a 5 prime number in it (eg 5/4 a major 3rd). AFAICT, the order of simplicity (dullness -> dissonance) on intervals is 2/1, 4/1, 3/2, 4/3, 3/1, 9/8, 16/9, 5/4, 8/5, 6/5... it's not exactly clear what the math is here.
Also, it's always really, really telling to me when someone shares a music theory without sharing a recording of that theory in action. The site I'm working on lets people use their keyboard to play with every scale, so you can verify that it's not just number play.