We weren't taught the alphabet until the age of about 6-7 and basic arithmetic at 7-8. We did begin learning foreign languages at age 6, however. In practice my older brother taught me to read and count well before the Steiner curriculum did, but I still think that the education was very valuable.
I think that creativity in adults is often stifled because they don't want to "get it wrong". People are afraid of trying their hand at a new skill or taking a risk on a new idea because they are "realistic" about their chances of success. Children just do it anyway. I think that Steiner schools encourage this attitude, and no doubt Montessori schools do the same.
There's a reason the really big hitters are often first-time entrepreneurs - they are naive enough to try. Creativity works the same way.