This is the whole idea of a distributed storage. You add many nodes (that are only confirmed to have the transaction in memory) to reduce the probability of all

This is the whole idea of a distributed storage. You add many nodes (that are only confirmed to have the transaction in memory) to reduce the probability of all nodes crashing during one commit and this is considered more reliable than locking the whole data storage to wait for a confirmed disc write. I'm assuming you mean commit==write to disc? ie. P(client queuing up too many requests and crashing because db is too slow waiting for disc) > P(5 distributed db nodes with the transaction in memory crashing simultaneously before it was written to disc)