What is the right amount of statelessness in a file server?

It is argued that although the stateless server model has proved quite useful to network file systems, statelessness is a means to an end and should not be an end in itself. The author maintains that statelessness can be a severe impediment to building efficient, reliable systems. He concludes that if its actual advantages can be preserved in a stateful system without too much effort, statelessness as a dogma should be discarded