Very interesting article about how music has to adapt for mediums like video games, where the player input impacts sequencing and pacing. That said, I think classifying this as "secret manipulation" is clickbaity on the part of the poster. The fact that the music influences the player isn't really a secret, any more than the fact that the visuals / controls influence the player.
Also they had music which was instrumented according to different moods and would seamlessly transition between them (e.g. Fast and slow chocobo theme)
The author of the internal tool to help the design team did a talk at GDC:
https://www.gdcvault.com/play/1023971/Epic-AND-Interactive-M...