I mean fuck. Someone has to be really stupid to buy into this (when Brendan Schaub is pushing this angle, you know it's a poorly formed opinion).
1. There have been multiple Brazilian champions since USADA came in.
2. Many of them train in the US now.
3. There are top contenders in every single division that are Brazilian. There are 3 challenging for a belt in the next 2 days.
4. It's not like all Brazilian fighters all suddenly had a drop off. Many are still doing well.
5. Just as many fighters from different nations (including the US) are getting busted by USADA.
Hence, this is a broken, baseless opinion. There is next to no evidence to support it and there are a huge number of factors as to why Brazilians are less successful than they were in the early days (notably, there are more Brazilians training Americans in BJJ and the likes than ever before).
I just don't get why people try to bash an entire nation of ahtletes for literally nothing.
It's just shows how shitty people many people are.