CS majors who cannot program applying academic theory without understanding.
I'm old enough to remember graduates rolling their own sorting algos, or building classes 6 levels of inheritance deep. While simultaneously creating massive if/else nesting, with tons of duplicated code, unable to understand how to use basic ideas like functions and recursion, even though I'm sure they probably had a whole one lecture on the subject, mixed in with whole modules on pointless compiler lectures.
Because that's what their CS degree taught them.
How both CS graduates and non-graduates really learn is by seeing what other programmers do in the industry, or by making their own mistakes.