Jack Ma never disappeared, it's a con that a lot of liberals pull. They tried to make the same claim about Peng Shuai who has made several statements to the public saying that she wished western journalists would stop harassing her.
And the reason why you haven't heard of the west doing it is because you're not studying primary sources. The newspapers won't tell you about it.
What you're describing is known as a ghost detainee. There's hundreds of them under the CIA's Extraordinary Rendition and Detention Program in secret prisons known as "Blacksites."
Ali Shallal Abbas was one of the few survivors who actually spoke to the UN about his experiences, and described how the CIA would rape and torture children in order to get their fathers to confess that they were working as enemy combatants. You can google his name to see the testimony.
These secret prisons exist all over the world, and you can find a map here of the ones that we know of:
It's laughable to compare Jack Ma's stories to that of real blackbaggings, he's a celebrity propagandist, like Nayirah al-Ṣabaḥ.
The western media would never treat real dissidents this way, just look at Julian Assange or Edward Snowden. Or Steven Kangas and Gary Webb. In fact, Snowden had to flee to Russia as a human rights refugee, that's the reality of things.
As for democratic centralism, it's a system set up as follows:
First you have labour unions or democratic councils depending on what is most practical in a local region, who appoint a delegate.
Then you have the delegation who set up a mandate and elect the politburo.
Then you have the politburo who sets up policies pending the review of the delegates.
Following this, the labour unions review the policies, and can proceed to instruct the delegates on any revisions or grievances.
And in such a way, a country with hundreds of millions of people can have direct influence over government policy.
I would recommend Xi Jingping's "On the governance of China" for more details on how it works in modern day.
