If every country plays by these rules except one, which uses mercantilist tactics to win zero sum games, that one country will have an advantage.
If every country plays by mercantilist rules, that advantage will not be there for everyone, since now the game has changed.
China's "unprecedented" growth was achieved by Japan and Korea during their peak growth period. Britain was the original champion of liberalization while the US was protectionist for much of its history. The EU is still quite a bit richer than China and has done well during this liberal period since nearly destroying itself in WW2. There are so many details you are choosing to ignore.
I actually don't fault China for executing their strategy, it certainly made logical sense and has lifted hundreds of millions of people out of poverty. I also don't fault Europe for executing their strategy and they have benefited from it - Europe was ravaged by wars over its history and one of the ways to avoid that was tight economic integration. Different circumstances require different strategies.
China doesn't have the domestic market they could have if they hadn't weakened their currency by transferring wealth from savers to the exporters.
Western countries: "OK."
China: applies protectionism, obtains unprecedented growth, steamrolls markets
US, Western countries: "Free market is obviously much better, protectionism and planned economies are inefficient and can't work, but... but... they're cheating!"
At least the US acts in their own interest (anarchy, i.e. the free market, makes sense if you're the strongest). What's pathetic is that European countries believe all the neoliberal dogmatic BS when we don't even benefit from it.