I can show you an example based on my experience. I won't this time because I believe people could draw the similar conclusion based what they know. Example from other famous people:
1 Mao said I can't always tell people the truth. Otherwise, we will not have politics.
2 Mao said the the bad things happen everyday. If the media reveal all of them, we would not have the reason to stay power.
3 Lin Piao said (when he was the 2nd leader) you can't do big thing if you don't lie.
Personally, I do not believe we must stop people from telling the lies. But we should allow people telling the truth.
Why does the government trying to stop people to go to Beijing to complain? Most of this people would not spend their own money and time to go to Beijing to tell lies.