iirc UCSC was pass/no pass from the start in the 60s/70s. Which didn't matter for the first few decades because it was mostly liberal arts. Then in the 80s/90s they started pushing into STEM. Those were the grads that had trouble with grad school and complained, at which point they added the letter grade option.Remember when UCSC did away with grades a few decades ago? It was a disaster. Students had trouble getting in to grad schools and employers recruited elsewhere, where student success whas easier to evaluate.
I started in 2000, and I was the last class/catalog year that still had the pass/fail option for all courses and could still get a GPA with only 2/3s of classes graded. All classes after that had mandatory grades for 75% of your courses. About a decade ago they also created a program that scans your written evaluations for key words and the algorithm assigns a grade.
Looking back at those days . . .