What I said "rarer commodity which gets selected more" means that you happen to be a rarer commodity AND you happen to get selected more. This is not equivalent to "if you are a rarer commodity, you get selected more."

What I wrote earlier, which is my claim up for dispute, is "if you come from a top US school, you are a rarer commodity which gets selected more."

Rarer commodity which gets selected more - Diamonds.
Rarer commodity but isn't selected more - independent fashion labels in Orchard Road