For example, does China's GDP at PPP 'equality' with the US mean it can fford as many nuclear submarines as the US, as many aircraft carriers? As many advanced state of the art stealth bombers, fighters, tanks, spy satelites and naval bases? No, it doesn't, all it realy means is it can afford as many roads and bags of rice as the US.
As soon as China starts investing in, developing or buying international standard technology and eqipment it has to start investing or spending international standard capital to do so, and PPP doesn't help anymore. Even in the case of 'soft power' such as financial support and investment in other countries, that has to be done in foreign currency. Suddenly the domestic purchasing power advantage of the Yuan becomes an equal and opposite disadvantage.