This. Note, too, that regardless of the rubric used by the institution, some students are still earning those top grades. Some rubrics just make the earning distinction clearer.
This same complaint comes up on the prep school forum every year. The New England boarding schools are notorious for grade deflation—straight scale, no do-overs, you get what you get and you don’t have a fit. Is there a problem come college application time? No. The colleges understand the grading policies of each high school and each student is evaluated only within the context of their school and where they fall among their peers who are under the same grading constraint—and some of those peers still manage to earn those top grades. Is it harder to earn top grades in those pools? Absolutely. If top grades are your primary concern, consider the pool you’re trying to enter.
Nothing more to say, IMO.