I mean some degrees are pass/fail. All ordinary degrees for starters, which includes medical (and I believe, dental) degrees. As I understand it, medical degrees (and possibly dental) do facilitate a level of benchmarking by comparing the students in each cohort against each other and ranking them in deciles. Which frankly would probably be a worse experience for the majority of students?
In that manner there is no grade inflation (you're either in the top 10% of the people in your cohort or not; you're either number 139 or 140 or not in the overall ranking) but creates even worse issues around the mental state of students realistically (especially if it then led to jobs only accepting those in e.g. the top 2 deciles or something), and I think would be complicated to introduce in a number of subject areas, practically. Also could lead to sliding standards without any kind of external checks (if there's no external system to ensure minimum if not stringent standards, it could be that functionally everyone on a given degree would effectively be failing or doing very poorly in the current grading system, but by the decile ranking system it would still be that 10% are given top decile and so on and so forth).
Switching to a letter grading system or GPA also doesn't really actually avoid any of the existing issues either, despite some universities considering it. It just resets the standard - the inflation would be inevitable in that system too, over time.