I think one point of confusion on this thread is the difference between being aware that admissions are competitive and that there may have been a legitimate conflict of interest for the coach, and being cut throat about the competition.
All the kids I know were nothing but encouraging and supportive of one another throughout the whole stressful college application process. And at both their high school and the college where my kid is now, everyone helps one another out in school, with study groups and collaboration and enjoyment of the shared experience of learning. Nothing cut throat!
But yes, many colleges do not allow alumni to conduct interviews when their own child is an applicant, because there is a bona fide conflict of interest. I think most people root for all the children they know, but their own child’s happiness is the single most important thing in their world.