The particular source here is not the Chinese government but the magazine the Economist and the consulting firm McKinsey. Both are very reputable.

You can go to China or some of the surrounding countries (SE Asia, Japan, Australia) and see for yourself. Or look at the sales reports from Apple. The massively growing Chinese middle class is quite a real thing.

Yet the reaction here is of scepticism, disbelief, denial.

I don't understand that.

No other topic (Europe, US, Africa, Middle-east ...) is met with same.