Point1. Education system which would strive for bear minimum outcome would be something like “not everybody needs addition, cashiers can take care of that”. (You will cut calculus, somebody else will cut multiplication table)
Point2. which iq range education system is optimised for? (Fair discission; though hard politically). Gifted people are random in population. If you teach and test only the bare minimum content, which 99.9% of population passes with flying colors, then gifted are undertrained and also harder to spot, thus under-utilised.
Point3. Memorization is useful. Even if one understands the concept deeply, the “cheat sheet” inside the head (i.e. memorised info) makes things much much faster. Memorization is abit like muscle-memory and or caching.