Alibaba and Amazon are 商人 (traders) passing things and money from one hand to the other making no added values to the society. They are like lubricant of machine, necessary and even critical at some point but never the core and foundation, should never to be allowed to take the major chunk of resources and profit. Whenever they become too dominant, they should be cut into pieces, but we are not going to remove them.
BYD and CATL are making real things, they are the machines. They will be encouraged to be big, but on the condition that they don't suffocate the tech development, that is not being a patent bully to stop competitions.
In principle, there should be NO dominant power in industry, NOT even SOEs. The only dominant entity is the State, the country. Chinese businesses are only to be large to compete with foreign powers, but not to overshadow the state power. They are the tools of the state, not the owner and ruler of the state. If you study the Chinese history, you will realize that it is always like this. And this is the very reason that China remained an unified state for more than 2000 years.
You are right in the core aspect, but there is a key guiding principle I think you are not making clear. The issue at hand is not industry or sector, but rather competitive power and fairness.
One of the basic principles about economics (and peoples and governments for that matter) that the west has forgotten is that all companies in all sectors seek monopolistic power and influence to allow them to wipe out the competition so they can just sit back to relax and enjoy an easy life afterwards. It’s basic human nature, but it’s something that must be resisted and fought else your industry and economy will fall into stagnant and decline.
Now, scale and size itself isn’t really a good determining factor in when a company has gone down the wrong path, because there are different minimal economies of scale that makes industries efficient and competitive, and there is no real magical threshold beyond which a company will automatically loose competitiveness.
Instead, it’s a psychological shift, and the best benchmark on when a company needs a change in leadership direction or even to be broken up is when said company stopped or slows competing through innovation and self improvement, and instead starts to try to stifle the competition. That is a key warning sign and red line, because as history has invariably showing, once a company with such a mindset is allowed to dominate the industry, they will stagnate the industry by using its market power to crush all challengers in the cradle all the while fleecing the public with rent seeking actions to abuse its dominant market power.
In the west, it’s far worse because once a company has grown big enough, it can achieve state capture by legally bribing politicians to write laws to effectively make their dominance legally mandated and change the very rules of the game to benefit the company at the expense of the public, country and even the world as is the case with Huawei and now TikTok.
Chinese regulators understand that a core part of their job is to watch out for, and resist companies that seek to behave in this way.
This is now the key fundamental difference between Chinese and western companies which explains why Chinese companies are absolutely obliterating their western competition in fair contests. Because while western companies stopped seeking to innovate and be more efficient and instead refocused their energies to political and legal intrigue to game the system, Chinese companies are forced to constantly fight for their position and survival through delivering better products and services for a lower price.