I don't think that's entirely true, or at least not true enough to nullify it. Companies are frequently posting record profits, so corporate greed is paying off. Exploitation of fiat is just one way they get their money. It's true that moving away from fiat will address those methods, but it won't stop things like union busting, coersion, wage theft, which is the most common form of theft in the US, and just general exploitation of the power imbalance.