No offense but this stance reminds me of telco people deriding the "best effort" Internet for serious commercial applications 20 years ago. A professor of mine was adamant VoIP would never take off because it just didn't work reliably.
VoIP didn't take off until it worked reliably. The same is true for "best effort" IP for various applications. Untold amount of person hours and investment have gone into making IP networks good (MPLS etc). Your professor's assertion about VoIP wasn't necessarily wrong, it just wasn't a complete statement.
The pure IP routing networks of 20 years ago were not full capable of making VoIP work well enough for general usage.
