The question is why is so much sex on Chinese websites. The Chinese government apparently has not done anything to control it. The Chinese Women's Associations don't care about it either. China does not have a strong religious network and most Chinese do not have a strong bond with a religion anyway so religions are not going to help much on this. However, sex is a big money maker for Chinese websites since most of the sexual titles are ads and it attracts more people to the sites.
I don't know if Chinese people are bothered by all of the sexual contents on the Net. But sex is part of people's life after all as Confucius once said.