Many teams took WGP very seriously. The only time top teams sent a real 'B' team to the finals was in 2012 when USA won it, with not one single starter.
I mean Serbia didn't give their best WGP in 2016 to make it finals. The same with China too. Their main players also skipped finals if I'm not wrong. But I remember it was not like this in past, in 2006 WGP and WCH finals were the same Russia against Brazil.