[Animats]

You can make a living as a mechanical engineer without using an equation newer than a few hundred years.

Have you seen what's happened to control theory in the last 15 years? There's so much new math that new PhDs are having trouble deciding which parts to learn. Control theory has imported much of machine learning in addition to all the classic control theory, and they want bounds so they know the machine learning parts won't do something stupid.

[throwaway2016a]

Sorry, that came out wrong.

I am absolutely not implying that there have been no advancements in mechanical engineering. Just that it is possible to find a job where you will not encounter them. I am confident you are right that PhDs are doing great cutting edge stuff.