Mutualism identifies the near-infinite problems of current markets and attempts to get rid of these by first of all getting rid of the state. If I understand it correctly, mutualism is essentially based on the cost principle. The cost principle means that “market actors themselves will engage only in transactions where the benefits are sufficient to pay for the real costs.”
This should in theory amount to a fair society. However, I am concerned with potential long-term effects. Since market actors all operate from a subjective environment, they might not have the knowledge needed to obtain the right price, they might not care about obtaining the right price, they might be coerced by their emotions or by a desire for increased social status that would affect which price they demand. In addition, there is no principle which prevents accumulation of capital. Accumulation ultimately leads to inequality, enabling e.g. organizations that could enforce property rights (like a state) and also poses a problems for e.g. people who are disabled. The market functions you’ve mentioned are designed to lessen the effects, hinder or slow down accumulation, but if you acknowledge the dangers of accumulation, would it not be better to abandon the system than trying to implement reforms that ensure that the system remains in place and only attempts to make it less bad? (By “remains” I refer to a time after mutualism has already been implemented, I’m not suggesting that mutualism is a mere reformation of the current state-capitalist system.)
You claim that communist and gift economies are hierarchical and thus not a better option. I think there are theoretical left-anarchist systems that would prevent hierarchies at least as well as mutualism, in addition to the practical example of sharing food employed by some San people. I think your idea of gift economies is based on cultures that have barter as their basis and only use gifts as social symbols, rather than basing their economy on mutual aid. Although I can’t present a functional example, I think such economies could possibly exist and that it’d be wrong to advocate for mutualism only on the grounds that there is no better alternative.
In conclusion, despite the concerns I’ve voiced, if I’ve understood you correctly, and if there is no better alternative, then I will side with you.