This is consistent with my experience flying out of PVG and my biggest gripe with CX out of China. Oftentimes, although the line is quite long, once I get to the C cabin it is only 50%-70% full. They do move Diamond/Emeralds to the front, but only when the line is very long.

The issue is allowing even basic Marco Polo members the benefit of "early boarding". It's no longer a benefit when over 50% of the plane receives it, regardless of class of service or elite status and dilutes the benefit for its elite members / higher fare customers.

I would be fine if they provided early boarding, but have standard Marco Polo members (Green I think) in a later boarding group from Diamond/Gold/Silver and Business by having them board on the Y side (what most other airlines I have experienced do). However, a system like that in Asia would be nearly impossible to implement effectively, especially on the mainland.