Why would he want to go to South America? Brazil and Argentina leagues are good and the quality might still be a little better then MLS, but why go when you have guaranteed minutes at a good team in MLS?
It seems risky with little reward.
I can see why players would want to go improve their careers and join La Liga, EPL, Serie A, Ligue 1, Germany or Portugal team and maybe a top team outside of the big leagues like Besiktas or perhaps Russia... but moving to Holland, Mexico, China, Argentina or Brazil seems lateral or not just slightly ahead.