This was hardly a tabloid headline, but the article was explosive anyway, with an illustration of a mouth gagged by layers of masking tape to drive home the message. China’s most powerful journalist was taking on Beijing over censorship.

Within hours the article attacking government controls – “Story about adviser’s free speech comments removed from Caixin website” – had been censored itself, but not before screenshots and reports of the financial magazine’s extraordinary challenge had rippled around the internet.

Editor Hu Shuli has spent decades nurturing her connections to China’s elite, able to read opaque political currents, a gift to go right up to the government’s red line and push it but “never cross it”, with two incarnations of a powerful financial news magazine.

So when she defied a climate of tightening government controls to publish the dramatic warning about official censorship, it sent shock waves across a China increasingly cowed by controls on media, activists and any organisations beyond the sphere of direct Communist party control.

President Xi Jinping came to power in 2012, and has spent the years since then consolidating personal power, in a dramatic departure from his immediate predecessor’s unofficial commitment to rule by consensus among the top handful of officials.

Xi has used an anti-corruption drive to tear down opponents in government and encouraged a personality cult, complete with adoring song-and-dance tributes, Mao-style merchandise and official nicknames to bolster public support for his leadership. But in recent months he has taken his campaign beyond the apparatus of party and government, intimidating and dismantling diverse sections of China’s small but vibrant civil society, its most daring media outlets and its bravest legal crusaders.

Targets have ranged from a legal centre supporting battered women to a network of Hong Kong booksellers behind scurrilous tomes about the private lives of communist luminaries, and one of the country’s most respected contemporary journalists and historians, banned from travelling to the US to pick up an award for his work chronicling a terrible man-made famine that claimed millions of lives in Mao’s era.

The crackdown has gathered pace as worries about China’s economy accumulate, timing that many analysts say is no coincidence. Xi is battening down the hatches because he fears opponents created by his drive for power see the coming economic storm as a chance to hobble or undermine him.

The opacity of China’s official data makes it hard to chart economic woes as clearly as in western economies. But even the government admitted that last year saw the slowest growth in a quarter-century, and the collapse of a stock market bubble last year gave the world further notice of problems.

Warning signs this year range from a slow start to the year for factories and retailers, and a recent announcement that nearly two million jobs in the beleaguered coal and steel sectors would go.

If there is anyone who is an expert at reading those tea leaves and figuring out how to walk that line, it is Hu Shuli Sarah Cook, director of China Media Bulletin

The economy is almost certainly growing slower than official figures suggest, said Steve Tsang, professor of contemporary Chinese studies at the University of Nottingham, even if it is still chalking up rates that would make European governments envious.

“So there is a need in that sense for them to exercise even stronger control over the narrative, hence the control of the media,” he said. The economy is not the only reason Xi is seeking to remove all possible sources of opposition, but its troubles are feeding into other drivers of a crackdown.

Increasing prosperity has been a cornerstone of Communist party legitimacy in recent decades as the government dismantled social safety nets. Any stumbling in growth or a wider economic storm leave Xi vulnerable to opponents massed in the corridors of communist institutions, keen to avenge losses of power and wealth.

“There’s still enough resistance from within the establishment who are not yet entirely comfortable with the way things are going within China and are using the economic slowdown to embarrass or undermine Xi,” Tsang said.

In an apparent sign of Beijing’s jitters over the economic situation, an analysis of leaked censorship directives showed that, between 2012 and 2014, the economy was only the seventh most sensitive topic for the Chinese government. Last year the economy became the second-highest issue on the censors’ blacklist, research shows.

It is perhaps no coincidence that a financial magazine with a track record of political survival has decided to take on the government now, when opposition may be cowed but multiplying.

Hu is too astute at reading political currents to gamble her magazine’s future on a quixotic individual stand against the government, some experts say. “If there is anyone who is an expert at reading those tea leaves and figuring out how to walk that line, it is Hu Shuli. And I don’t think she would take a bold an action as that … if she didn’t think there was space to do that,” said Sarah Cook, the director of the China Media Bulletin. “It is interesting that she chose to do this now.

“I think she was reading that there are an awful lot of people who agree with this fellow [government adviser Jiang Hong, who talked about free speech in the article that was removed] and are going to be upset that someone like that was censored.”

For years, crusading lawyers, journalists and activists have been pushing at the edges of China’s laws and official systems, carving out a little more space each year for those cheated, abused or mistreated to hold the powerful to account in a one-party state.

Supporters saw them as a small but important check on official abuse, and key to China’s healthy growth. Xi has obviously come to see their potential as a dangerous source of opposition to his rule, as more important than their potential role in building and strengthening the “China Dream” he has put at the heart of his rule.

Jerry Cohen, a veteran China law scholar who has studied the country’s political landscape for more than 50 years, said Xi’s offensives against human rights lawyers, internet freedom and now the media shared a common thread.

“The government faces Promethean tasks. Xi Jinping has taken on these enormous burdens of dealing with corruption as well as his political opponents and trying to improve the situation with respect to pollution and trying to improve the economy.

“And he figures he can’t do these things without absolute iron discipline, unquestioning acceptance,” he said. “We cannot have a questioning of the leader.”

One of the great mysteries of Xi’s drive for power is what he aims to do with his absolute control. In the early years of his rule, many hoped he was tackling corruption and shoring up his position so he could steer China through more years of controversial and sometimes painful reforms. Many were inspired by the record of his father, a hands-off reformer allied to Deng Xiaoping, who in the early 1980s called for ordinary citizens to be allowed to openly question the country’s rulers. But comparing the two men appears to be a mistake, warns Cohen.

“[Xi Zhongxun] said you shouldn’t prosecute people for having different views and you shouldn’t kick them out of the party ... People should be free to express themselves,” said Cohen. “Well, Xi, the son, has just gone to the opposite extreme and in the past six months he has really gone off the deep end.”

And there are concerns that the quest for power could become an end in itself, given the still considerable power of many opponents more than three years into his campaign.

“The fact that they exist, and are using every opportunity to show they have not been eliminated, proves the need for Xi to reinforce his control even more, so you get a cycle,” said Tsang.

“He’s still not in a position that can push for big reform agenda: there is a risk that he gets trapped in a cycle of consolidating power for the sake of it, even though it’s not where he started or what he intends to do. We are in the situation of not knowing if he can get out of it.”

■ Hu Shuli was born in Beijing in 1953, to a long line of journalists. When she was 13, the cultural revolution hit China, school was suspended and Hu travelled the country as a Red Guard, then spent eight years in a remote hospital.

■ Universities reopened in 1978. Hu won a place to study journalism, then joined the Workers’ Daily.

■ In 1989 she was suspended from her job over the Tiananmen Square protests; she had taken part and called on the paper to cover the bloody government crackdown.

■ In 1992 she went to work at the more independent China Business Times, building up impeccable contacts with a new generation of reform-minded officials.

■ Hu set up Caijing magazine in 1998, backed financially and politically by some of those contacts.

■ 2010 Hu left Caijing after a dispute with its owners, and established online Caixin to continue her crusading journalism. Plaudits include the Ramon Magsaysay award in 2014, sometimes called “Asia’s Nobel peace prize”.