I imagine that if you're cramming for a test on how to do differential equations, and you're able to pass that test, you actually know how to solve differential

I imagine that if you're cramming for a test on how to do differential equations, and you're able to pass that test, you actually know how to solve differential equations. "IT People" cramming for tests and memorizing the test for those certifications is a testament to the failure of those certifications, not for certifications in general.