Ok, I read the chat in your link, but is this backed up by factual Sport Interactive information or just based on users opinion?
I'm just going to talk about my experience:
I play long save career with PSG, and buy regens with at least 4 stars. Some of them come from Argentina or Brazil. They arrive at my club when they turn 18. I keep them one season in my reserve squad, then loan them for at least 2 years (in Spain when it's possible to get the Spanish passport). They ALWAYS become homegrown, any explanation then?