A person generally cannot effectively, fluently, convincingly regurgitate an argument without understanding it, and the act of memorizing a variety of different positions primes the brain to handle all of them with greater depth and adroitness. Mill greatly underestimates the power and benefits of memorization.
I think most people would agree that memorization and a standarized 'one-size-fits-all' approach are inferior to teaching methods that are (onstensibly) creative, 'active,' and individualized.
I couldn't disagree more strongly. It's a false dichotomy. All learning -- all -- starts from and depends upon memorization. Is that its only the goal? Obviously not, but memorization gets a bad rap because it's viewed, incorrectly, as contrary to or in competition with more active, creative intellectual enterprises.