There’s the problem!
I’ve had this experience many times — people will internalise their limitations and assume that their best is the best possible. Etc..
When a junior employee just casually proves them wrong, calling the emperor naked, that makes them feel inadequate and even ashamed.
I’ve been involved in many similar scenarios. Often there is a history of meetings, consultants, vendor techs, etc… trying to fix the problem and then a grudging acceptance and business workarounds. To suddenly reveal all of that as a lie is to undo established history. It’s like trying to close down the Vatican and tell all the priests to go home because you found a “neat proof” that there is no God. To say that you’ll experience some disbelief and resistance to your ideas is an understatement!
I had one of these moments where I got a nightly report batch job down from 3 hours to about 5 seconds. The customer turned red in the face, screamed at me, accused me of lying and stormed out of the meeting room.
Turns out that guy had to stay back each night to make sure the job ran successfully and so that he could sign the print out officially. He’d accepted the impact on his personal life, after many arguments about his work hours with his wife, etc…
To have all that sacrifice and suffering instantly made superfluous!? Ouch.