There is a fellow I know who gives embedded design seminars, and he -- intentionally -- puts up one slide that has an error in showing Maxwell's Equations. He notes that in Europe, especially Germany, almost every time he puts up that slide, someone politely points out his "typo". In the USA? He said about 1 in 50 seminars somebody does the same. If you are doing engineering, and you don't know cold both multi-variable integral and differential calculus, you have no right calling yourself an 'engineer' IMHO.

Your example will only resonate with a small minority since most of us here are web and CRUD jockeys. Also, your claim to have "seen this sort of thing again and again, in diverse fields," is patently disingenuous. Even the most maths-intensive groups in tech deal largely with discrete methods.