I wonder how would they know which accounts to close and not to close. I would guess they would read some of the account's information or messages. So your information is not private. Us a large "search" and find information.
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In response to pressure from Beijing
The Chinese company behind the popular messaging app WeChat said Tuesday that it had shut down 20 million accounts for being
linked to prostitution.
Tencent Holdings Ltd. dubbed the massive shutdowns “Thunder Strike” in a blog post. WeChat is a three-and-a-half-year-old micro-messaging site with an active-user base that just surpassed 396 million people—meaning Tencent shut down 5% of active accounts. The purging of accounts came in response to a May government crackdown specifically against the platform. Many use the app as a news source in a heavily censored web environment, but the government said it also being used for harmful practices ranging from fraud to terrorism to prostitution. Authorities had promised to “hold service providers responsible if they do not fulfill their duty,” according to Chinese state media outlet Xinhua.
http://time.com/#2851900/china-wechat-prostitution/