Why do south american teams do so well in the world cup?

I've always wondered why south american teams do so well at the world cup particularly brazil and Argentina.

I thought maybe it's the number of games they play in qualification. They seem to play twice as
many as we do in Europe that it would give their players coaches and staff longer to get to know each other and figure out the answers to all the questions they will be asked on the pitch. It could be the passion for football within the country. That will provide many highly talented players and coaches and they will all be used to the grilling they get at a list world cup. 

Seeing that Argentina were just thrashed 6-1 by bolivia at altitude highlights that they all have to play in such varied environments from altitude to sweltering heat and oppressive humidity and then extreme cold. The continent is so vast they get to regularly perform in all kinds of environment. The best team can falter heavily to a weaker team playing in difficult conditions. The number of games they play encourages building a large resilient squad that can survive the intense rigours of the qualification campaign that makes the finals seem relatively straight forward. 

I don't think its any one of these points that makes this continent so formidable i think its all of them and many more.I think it's worth considering this in our quest for world cup glory.