Paradoxically, as long as all information regarding the Tiananmen massacre in 1989 is being censored, there are people whose job it is to not forget to forget it. This means they'll have to remember to hide this sensitive information. So in a way, by taking so much effort to hide this information, China (and all countries and companies sucking up to it) are keeping this information alive. And (hopefully) eventually, these people will ask themself why it is necessary to hide it.