In Pilger's long documentary, posted recently I think by Tomski, there were several memorable quotes, one being "While the US has many parties but one policy, China has one party but many policies", and it seemed fairly obvious to me why: If China had many parties, as Hong Kong does to some extent, there would inevitably come about just a single policy - and it would probably not be a chinese one.
The opportunities and technologies for outside intervention are that great.
Another memorable quote was "In the 1980s Gorbachev chose to put political reform before economic reform and China chose to do the opposite, and which of the two of us had more regrets over the outcome in the subsequent 2 decades?"