Your critique falls flat (pun intended) because there is no DTMF here.
Also, this video is a chopped-up edit from a session of real music performance, rather than someone's original composition. Many commenters seem oblivious to this distinction.
The very first notes are supposed to be a dial tone followed by the note run on flute+clarinet representing the dialing of a phone number. That is supposed to be DTMF, with the flue being the high tone and the clarinet being the lower tone.
It's hard to recognize as not only would do the frequencies of the DTMF standard likely not line up with the fundamentals of the 12-note western scale, but these wind instruments don't produce anything close to a pure sine wave- they have lots of harmonics, and with two of them overlapping it's hard to discern what the phone number was supposed to be.
Your critique falls flat (pun intended) because there is no DTMF here.
Also, this video is a chopped-up edit from a session of real music performance, rather than someone's original composition. Many commenters seem oblivious to this distinction.