Is the barter system one that mitigates unfair accumulation?
If you barter with currency-likes (in particular, storable items) it only slows the rate of accumulation because a barter economy is so inefficient. However, currency-likes are less valuable in a barter economy because you need to find a person who is interested in your wealth for it to become a source of power. If you barter with non-storables, accumulation is impossible. It's not clear that this is an advantage. In general, barter economies are not an equilibrium; currency is just much more convenient, and unless you found a religion that says currency is evil, people will just go back to it eventually. Even religions have not been found to be insanely effective at imposing this type of law - the majority of people will gravitate towards what is more convenient.