While it is true that all economic systems have specialization, so far capitalism seems to be most efficient in self-organizing it. The reason is explained before: wherever specialization yields a high margin, people jump into that gap. As the gap fills, the margin gets lower over time and everybody pays lower prices for the same goods.
There might be other economic systems that also foster this kind of self-optimization, and don't have the negative effects caused by capitalism, but we haven't seen them yet.
Capitalism is also good at building the right capital. Capital in this case refers to intellectual and physical goods that produce other goods, such as machine tools, construction equipment, metallurgical processes or freight railroads for example. Building a lot of the wrong capital and using it inefficiently is a problem that has always plagued centrally planned economies.
Capitalism isn't defined as "non-centrally-planned economy", it's specifically privately-owned capital. If that private ownership is concentrated enough, then lots of things are pretty centrally planned. And non-capitalist economies include ones that aren't centrally-planned.
