I went to U of of Chicago in the early ‘80s, and grade inflation was already a thing EXCEPT at U of C. That wound up hurting grads whose grades would have been better at Dartmouth or Brown.
In the 1970’s most graduate students in the economics department earned at least one C in their program. Many had more than one. The department did not have a rule 2 C’s and your out. It was not considered a good grade but also not considered a bad grade.