For example, from the perspective of an algorithms junkie, there's literally 0 way an algorithms professor with algorithms research published would forget any of the basic algorithms they teach in an introduction to algorithms class.

Now what may happen is forgetting what it's like to be a naive, 18 year old freshman in college, and not somebody embroiled in academia for the past few decades.

But the audacity to suggest that it's even remotely within the norm for professors to not know their own material... wow.