Anyone who advanced that ‘defense’ has a poor understanding of economics.
Risk is not an essential element of capitalism. Some investments are effectively risk free. ‘Disproportionate’ return seems to be something you’ve just made up. There’s no mention of the proportionality of returns in any economic treatise I’ve ever read.
Lastly, there’s nothing to defend. There’s simply the observation that if there is no return on capital then there’s no reason at all to provide capital. Nobody has ever come up with a working alternative.