Please don't interpret this as the usual internet activity of saying, "unless you read this long article I win the conversation." I genuinely just want to provide some info.
Also, I chose this article because a peer-reviewed, published academic article passes the rightfully rigorous standards of this site.
Meanwhile, even the article you linked professes that the US gave tons of aid to the South. Even if the US supported some pretty brutal dictators, it clearly had a positive effect on the S. Korean economy. Today, S. Korea is more democratic and prosperous than N. Korea by far, thanks in part to the US. Blaming America or European powers or even Japan for North Korea's woes really doesn't make sense.
Some I just guessed..