If authoritarian government is by default this effective and easy to success, why most of them failed?
Because the decision makers will inevitably make very large mistakes, and generally don't have the ability (or capacity) to course correct.
The western system is far from efficient, but it generally lands on the right solution in the long term.
The main reason why it lasted so long in China is because it is now operating in the economic system and condition it was designed to work under.
Indeed, this system of governance was designed by Lenin and his cronies precisely to operate under and regulate State Capitalism. It's not designed to work with a planned economy, or with a completely capitalist economy, or with an agrarian economy, but explicitly with State Capitalism (see: NEP).
Secondly, it's not actually supposed to last. This kind of government was designed to last more or less 70 years under the correct economic system, it wasn't designed to last forever.
China happens to be a case of the government system operating in exactly the correst economic system during the period where its supposed to work.
The rest of it is just typical "democratic" centralism, self-criticism, a strong ideological backing, and the ability for flexibility and reactivity at the local level, as well as a good dose of fear.
Also maybe the exact definition of "state capitalism" could still be somehow controversial. People would describe the system in China especially in the past 3 decades or so as very much wild west capitalism. Private companies competed for survival and market shares like crazy without much regulation at all. Regulations have only been picking up in the recent 5 years or so. Sure there are state enterprises especially in more inland regions, but they are not really the most important drivers of China's economy boom, especially in manufacturing and exports.