I don’t quite understand. If grades are not moderated, won’t everyone get a poor grade when the exams are tough and As when exams are easy?

Since the papers were easy this year, I suppose the national average should be higher and standard deviation lower. I took the national average as 79 and standard deviation as 10. Therefore, a raw score of 77 marks is converted to a T-score of 48 (T-score of 50 = national average per subject) or B grade rather than an A grade which would have been the case during school examinations. Not sure if my analysis is correct. Any ideas?