I somewhat agree with you, however I do not know the US system very well. In Germany university admission is done by grades alone; however we don't really have elite universities like the ivies, but all universities are at a rather mediocre level.

For example I could have easily gone to med school with my grades, which is one of the majors with the higher grade cutoffs, but it is maybe open for the top 10-15%? At this level I don't believe parental involvement matters too much, everyone at age 18-19 is mature enough to know: OK, if I want to study medicine, I should try to get these grades etc...

But if admission is based in the 99,99% area, I don't know if a system based on merit alone is "fair". If I look at areas like competitive sports or piano competitions etc., I would believe at least 2/3 of the contestants at the national stage had "helicopter parents" relentlessly pushing them, often against their own will...

So having a "tiger mom" simply gives you a huge competitive advantage over "normal" kids/families. So if your system is based on ideas like affirmative action, where people from disadvantage backgrounds get a boost, it seems sensible to give people from advantageous backgrounds a detriment.