The USA has always had a middle class. It never decided to create it, it just naturally happens in a free market.
Further, we are in a noticeable amount of ways not a free market. If I took my car engine (the free market) to a mechanic and said "It's not working after I just made a couple of random small changes to it", the mechanic would rightfully laugh me out the door because me just meddling with a complex system, even if its only a small amount, can have disastrous side effects.