When social media emerged in China almost 10 years ago, my peers and I were excited. Here was a space where we could share everything, we thought, from bits of our daily lives to our unvarnished views on public affairs. We were naively optimistic back then about the prospect, as a famous phrase at the time put it, of "onlookers changing China".

Things did not turn out that way. Nearly a decade later, the growing silence on social media when it comes to sensitive public issues is deafening.