Hmmm. Your choice of words here has just sparked a realization for me.
Before you said this, I was completely on board with the original post. But in juxtaposing effort with value, it illustrates that we're basing the idea on the Labor Theory of Value. That idea seems intuitive, and Adam Smith wrote about it 250 years ago. But it turns out that LTV is very wrong. Economists showed that effort does NOT impart value.
But researching this a bit, I find that it still predates Marx. I find:
Sir William Petty, 1662: "If a man can bring to London an ounce of Silver out of the Earth in Peru, in the same time that he can produce a bushel of Corn, then one is the natural price of the other."
More important, it seems that David Ricardo (a big name in economic history), in 1817 latched onto what Smith had written and states it quite definitively.