The author isn't just saying that they themselves couldn't write a Tic-Tac-Toe simulator the first time they were exposed to the problem. The author is saying t

The author isn't just saying that they themselves couldn't write a Tic-Tac-Toe simulator the first time they were exposed to the problem. The author is saying that after watching candidates work this problem "for years", apparently not even a high level algorithmic idea stuck with them. This is... surprising.