Why didn't the Chinese government also block VPN if they didn't want their people to know the information outside of China?

Link: https://www.quora.com/Why-didnt-the-Chinese-government-also-block-VPN-if-they-didnt-want-their-people-to-know-the-information-outside-of-China/answer/Reina-Stewart-2?ch=18&oid=235721146&share=1aaaeb9f&srid=EO0pi&target_type=answer