Simply they do not trust the RVSM system. If all fly 3 / 6 NM right of track then the wake turbulence can hit you still, SLOP is something diffrent.
Spot on!
It is true that China is far behind the rest of the World, directs, shortcuts no possible. I had a discussion once with the Controller, (poor Guy) because the Squall Line was not conform with the Military requirements. My only option was either right by 60 Degrees or 180 Degrees back, STBY was the answer, a CB does not wait longer as the Shanghai Frequency was jammed as usual and the chatter is almost 24/7.
I only ask twice, the third time I informing them of my new heading until clear of weather (sometimes this triggers some very interesting exchanges on the frequency).
Another problem you face usually in Chinese Airspace is the early descent when you fly to a Chinese destination, 200 NM before to of descent with 2000 ft per min or greater
I never accept rates of descent and I tell them so. If everybody did the same, they would have stopped this stupidity by now.