I believe what he is referring to is the idea that you can't tell the difference between eg. an "augmented second" and a "minor third". One is written e.g. C-D#, one C-Eb.
I've always found the distinction between these two types of interval largely pointless - for exactly his reasoning. They sound the same.
Potentially they are useful in discussing theory in writing, potentially they are relevant when tuning using non-equal temperament. But knowing this distinction doesn't help you make music that sounds good.
An ear trained pianist, for example, would not distinguish these two intervals, and I would argue that would not be a limiting factor to the quality of music they could produce.
Potentially they are useful in discussing theory in writing, potentially they are relevant when tuning using non-equal temperament. But knowing this distinction doesn't help you make music that sounds good. An ear trained pianist, for example, would not distinguish these two intervals, and I would argue that would not be a limiting factor to the quality of music they could produce.