“I agree that legacy admits at the most highly selective colleges are “not of the same caliber as the rest in terms of academic ability and history”. They are typically stronger.”
The evidence (Espanshade, Harvard lawsuit, other studies) says they’re not stronger, they need a bump, additional preference as ucbalumnus notes to be competitive. Espenshade says they get a 140 point bump in admissions, meaning that if Asians are at say 1450 for the ivies, legacies are at 1310.