That strikes me as being remarkably heavy handed given that these same schools seem to give even more advantage to non-Asian minorities (https://en.m.wikipedia.org/wiki/Legacy_preferences).

Many folks, especially HNers, seem to think that entrance to elite schools should be purely (or mostly) based on academic merit. Any school that would choose to do that would be shooting themselves in the foot in a number of ways. For example:

1. Athletics would suffer. Even in the athletically weak Ivy League, winning sports teams increase donations directly and indirectly as well as alumni involvement.

2. Pure merit admissions would negatively discriminate against many minority applicants for various reasons that are fairly well documented in research.

3. The social capital of the institution's graduates would suffer greatly. Elite schools tend to have a healthy mix of people who are great producers and people who are great facilitators based on their personal networks (e.g., rain making, getting funding, doing sales, etc.). These two groups do a good job of scratching each others' backs. If the ratio skews too far in one direction, the balance will be broken and both groups will be less effective.

For the most part, legacies either would get in anyway (i.e., without legacy preference), or they are filling in the mediocre parts of the each class while providing some sort of benefit to the school (e.g., strengthening alumni network, strengthening school community, school donations, propensity to encourage their potentially talented progeny to apply to the school, etc.).

I assure you that no highly talented applicant with an application that accurately represents them is losing a slot to an elite school based on a legacy (or an athlete, or a z-lister, or whatever) -- either they probably just aren't as talented or interesting as they (or their parents) think they are,
or something went sideways with their application (e.g., recommendation writers not being skilled at writing high quality recommendations).

As I have said before in other replies on this topic, only 10-30% of an elite school's entering class is "interesting" based on my own personal definition of interesting (having one or more of: creativity, high capacity to learn and synthesize new ideas quickly, true leadership/charisma, etc.). These are all easy admits to any school they apply to -- no perceived strike like non-legacy will hold them back. The rest of each entering class looks remarkably similar and mediocre in comparison, and the admission committee has several vectors they need to consider when filling those slots. Legacy admissions is just one of those vectors, and I think it's a totally reasonable one given the other vectors that are also considered (e.g., affirmative action).

Some people seem to think that admissions to an elite school is a golden ticket, and that's a half truth. Elite schools definitely open doors that non-elite schools don't, but the benefit often ends there. The skilled/interesting folks take the opportunity and run with it, and the vast majority of others just fade into mediocrity.

This is a favorite topic of mine that I think is often misunderstood. I am happy to share what I know to folks who are interested, so please feel free to ask questions -- I will answer to the best of my ability.

Apologies for a reply that is a bit beyond the scope of your comment, but this is as good a spot as any in this thread to make this comment.

Source: Me. Attended and worked on admissions committees at two elite schools.