Was capitalism responsible for the wars waged in that region by the Aztecs? Was it responsible for the massive losses of life in the USSR and Mao's China? You can't just say that because X country is capitalist, everything that happens in it is because of capitalism. It's just an economic system, that's all. Projecting it's effects beyond the realm of economics requires some justification.

Capitalism didn't originate the concept of resources, or politics, or even money. How can you justify blaming Capitalism for things that happen just as much, if not many, many orders of magnitude more in non-capitalist societies?

Conversely I think it is justifiable to attribute the enormous economic gains of that billion people to capitalism directly. It's an economic system and we're measuring economic gains directly attributable to investment, often replacing decidedly un-capitalist systems.