Whenever these posts pop up no one really seems to ever actually consider admissions selectivity in the supposed grade inflation.
Most universities in the US are actually pretty easy to get into- but Yale and Harvard certainly aren't. Yale's admission rate is 4%. Harvard's is 3%. These have decreased over time to record lows. Their applicant pools have ridiculous academic qualifications. If the applicants are stellar students in high school why is it so outlandish they are doing well in university courses too?
Not to argue there couldn't be any grade inflation, but you can't really compare across institutions when admitted student pools are so extremely different.