Which sites should I block?

Why are Twitter, Facebook, YouTube, and many other foreign websites blocked in China?
Observation 1 - Most reporters fail to realize that many of these blocked sites are rarely visited in the country. Chinese netizens don't visit English sites! Only the foreigners are blocked in China.

Observation 2 - Chinese social networking sites, video sharing, and blogging sites rarely get the silent treatment compared to their foreign counterparts.

So what is the Chinese government really protecting? Assuming censoring information from foreigners in China isn't the goal, I suspect the Chinese government is largely using it to protect their local internet industry.

What do you think?