I would encourage everyone to keep two things in mind:
1. Our own individual experience is different than the experience of others. We should be careful not to invalidate other experiences because we didn't experience the same. For example, at my Masters school, there is a scholarship for visible minorities in Canada, which I qualified for as an Asian-Canadian. I grew up in an area of Canada with a lot of Asian-Canadians and for almost all of my childhood, I was actually surrounded by people that looked like me. Definitely did not feel like a minority. But this doesn't mean that I should say that Asian-Canadians aren't minorities and that the challenges that Asian-Canadians face aren't real and significant. Therefore, while I might choose to not discuss my visible minority status in my applications, I should not look down on others who do, because I do not know what their experiences are.
(Note: it was many years after starting my MSc that I realised, like Izaac said, while Asian-Canadians/Asian-Americans aren't under-represented in academia, you will find very very few Asian-X faculty members in senior positions like Deans and Department Heads. Just saying.)
2. Quotas are not the way to go, in my opinion. And I don't think it makes any sense for a department to be expected to be "lenient" on minority students in order for them to graduate more easily. This is actually doing more harm than good and I think these examples are often thrown around by people who don't believe in the importance of diversity to discredit actual programs doing actual good. Students in minority groups do face extra challenges in academia that are not easily visible to those in majority groups. You asked for some counter-examples, and I would encourage you to read about unconscious bias and microaggression. Here is a link to get you started: http://womeninastronomy.blogspot.com/20 ... sions.html
. Honestly, I think it's a little funny when people say because of "diversity policy X", it is easier for "people in group Y" to succeed when the whole reason that "diversity policy X" even exists is because studies showed that "people in group Y" are in fact not succeeding.
In addition, I think it is incorrect and wrong
for graduate programs to only select based on "educational criteria". We are humans and it's important to select based on humanistic criteria. I say this because each person's path through life is shaped by the identities they have and when we only look at educational-related ones, such as GPA, research experience, GRE scores, then we are ignoring the rest of the story. We are purposely removing important information!
For some concrete examples of what I mean, consider this hypothetical situation where you are trying to select an undergraduate student for a summer research program.
1. How do you compare a student with a 3.7 GPA and have received a full ride scholarship for their university vs. another student with a 3.7 GPA but is working 20 hours/week to pay for tuition?
2. How do you compare a student who lives on campus and has lots of extracurricular activities vs. a student who is a commuting student and has very little extracurriculars?
3. How do you compare a student who have had a couple of summers of unpaid volunteer research experience vs. a student who have had no research experience but worked every summer in non-academic work (e.g. painted houses).
There are no right answers, at least not that I know of. I meant these questions to raise the point that different applicants would have had different opportunities to achieve certain things and if we limit our search to only academic related criteria, then we are putting those with fewer prior opportunities at a disadvantage. And, generally, those with less privilege have fewer opportunities and thus they are going to be the ones disadvantaged.
I've said it before, but I think the answer is to evaluate graduate school applicants as entire human beings. And I know many schools do this. For example, I've talked to faculty that list important things they look for in a graduate student and they include things like "perseverance" and other so-called "non-cognitive" skills. An example where this could apply above is example #1. The candidate that maintains a 3.7GPA while juggling a lot of other responsibilities demonstrates some qualities that might be desirable in a graduate student.