Excess profit is a stupid fairy tale told by the bearded idiot. It is literally impossible to not retroactively 'exploit' somebody. Not just in the practical 'need to know what the end user will do with it to avoid them making an excess profit' but if the value changes over time they need to somehow predict that perfectly or else be guilty of exploitation. The notion itself always assumes that the capitalist should get absolutely nothing because he isn't doing "real work" and then ignores how things fall apart without them, or how much that the worker would have to do to substitute for them.

Ironically the communists have managed to out-greed the capitalists through this one fantastical concepts. Capitalists accept that they need to pay people to get their inputs and try to make the most of it one way or another. Communists are kept up at night at by the thought that somebody else may have made a penny off of their labor, and think that they need to murder them for it.