They're not really blaming capitalism for anything though? They're just explaining how it works, and they're right. In a market driven economy, you are paid for having a skill or some knowledge based on the demand of that skill or knowledge and nothing else. In the same way as the quality of your house has little bearing on it's value when compared to it's location. Not a criticism of capitalism.

TIL repeating the definition of capitalism is blaming capitalism

It wasn't capitalists, it was the invisible hand of the market.