I see no point in making a differentiation between mechanism and the methodology to which that mechanism enables the most exploit.

I disagree with your thought that capitalism optimizes work. It either ensures work is done many times over in parallel (competition) or arbitrarily based on the whims of the owner class (olig/monopoly), and that alternative/more efficient means are snuffed out where a more profitable option exists. It's an unstable and inefficient system that relies on civil expenditure (bail outs, infrastructure, etc) to function.

The capitalist system that requires you labor to for food and shelter is exactly the same mechanism that rejects people, pushes them out, exposes them, and props up the wealthy class. Your "Social Darwinism" is a fundamental consequence capitalism, not an unrelated ideology that just happens to exist simultaneously. Capitalism drives people to do [more] evil. Then they rationalize their behavior to protect their ego and power.