You're actually just proving his point as everyone you listed is considered big misses by MLB scouting standards.
Everyone thought Altuve was too small, Donaldson flew under the radar and I've seen several pieces from baseball insiders that the straight missed on Goldschmidt.
The interesting thing to me is that Betts was one of those guys who was a super athlete when he was drafted. He had plus speed but was really one of those "he's good at everything he does," lets see what happens guys.
He is the perfect example of a guy with plus plus athleticism putting in all together.