One problem with the idea that “we are good and you are evil” approach to politics is that it ignores that fact that there are a lot of idiots on your side and some pretty smart rational people on the other. There is the “traitor reflex” that when people suddenly get nationalistic it’s easy for people that call everyone else “traitors” to gain attention even if they can’t really get power.
Fortunately, in the case of China, the “call everyone traitor” group gets a lot of internet exposure, but they aren’t in a position to get power. It seems that the Chinese government is calling on people to be “rational” which also fits in with the fact that it’s really, really difficult to sustain anger and fury for long periods of time. So we are probably on the tail end of the anti-anti-China demonstrations.
The classic example is the dangers of “idiot nationalism” is Serbia. If you are a nationalist, then presumably you want your nation to be rich and powerful, and if you look at Serbia now, its much less rich or powerful than it was in the late-1980’s.