this is a good metaphor for becoming a senior engineer. senior is a terminal level; you must advance so far, most won't advance farther.
a few will go on to staff or principal roles, just like a few doctors will go on to become medical administrators, instructors, or inventors.
Idk, do we do that "rightly"?
Doctors understand that at some point you are a doctor and then you doctor forever unless you choose to change to a deferent set of responsibilities
I wonder if we need to have a stronger concept of what terminal levels look like