Well if this is true, I don't know. Normally Business Internet packages are not affected much by blocking because the ISP's tend only to keep them to residential. With the improvement of QoS of networks and overall network speed, its really hard to monitor transmitted data. Packet intervention and firewall policy's to block websites tend to increase router load and lag on the network. Thats the technical aspect to it.
If you study on porn you will know that real life SIMULATED tests conducted tend to point 50% 50% saying that stopping porn tends to increase rape cases and while other reports say it tends to reduce rape. But the mentality of 90% of the world population is that stopping porn forces them to go for alternate means of pleasure, which SIMULATED tests don't account. It may be rape or dirty sex with prostitutes. Thats not good for the population as it increases Sexually transmitted deceases which is why watching porn and masturbation is considered 'SAFE SEX'.
There is a myth that stopping pornography in the country improves children's studying abilities. Its similar to the myth that says masturbation causes spinal injury. Rather, it tends to promote more under-aged pregnancies and abuse and more serious repercussions on the future of children. But arguments are there. As I said its 50% 50% on theory, but on mentality is 90% to 10%.
Attempting to control personal space of people is very sensitive and very dangerous. Caution is to be taken.