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Education quality at most top universities is middling, they’re designed for smart people who will reach for knowledge. Being around the best people drained from around the world provides fertile ground for that.
Virtually anyone at a top tier university would be 100% capable of learning their material and making good grades on it with the textbook alone. Combined with online resources, even easier. The quality of instruction isn't all that important for these schools, it's the decisions around which material to present and how to present it, which they can do because they attract the best talent.