One distinguishing feature might be that the author understands the code and how it fits to their specific use case. As an alternative to trying to adapt and integrate a big complex piece of tooling into a localized application it may make some sense [or not].
To put it another way, tools like Redis are often designed and documented and optimized based on assumptions of large scale deployment and sophisticated engineering teams. While this doesn't preclude small scale and/or individual use, it still assumes a significant level of time commitment: for example, a reasonable understanding to achieve a 95% chance of successful deployment on a random application might require 8-developer-weeks of experience. On a team of four with an average of six years experience, there's a good chance that some of the necessary time commitment has already occurred. On a team of one there's going to be a deep dive even if the person already has half the required experience.
I mean suppose Redis does everything that is necessary except in terms of persistence model, or more likely it did everything fine until now when I realized I need a different persistence model. Sure it's a rabbit hole either way, and neither is necessarily better, but changing the persistence model of my code to suit my use case may be easier than kludging on or choosing among other people's kludges.
To be clear, I'm not arguing that the author's use case is a snowflake. What I am proposing is that the author's knowledge and skill set and time availability probably are, and writing a key value store may be more productive and efficient than figuring out how to adapt and apply Redis.
And the readme doesn't mention redis at all - is it possible that the author is simply unaware of the existence of redis, and has simply reinvented it? Because that would be absolutely hilarious :p
It would also be a fun project, though. Redis is something that I really wish that I had had the opportunity and the vision to build myself. Classic data structures as a service; too cool for school.
At first I thought there is a chance that someone thought about the advantage of the same thing. I have always thought that cache products that lets you build your custom distributed data structure would be a marvellous thing and while Redis does not provide the same feature it sort of allow one to build much more complex cache data structure using its primitive. But given that its implemented as a single threaded async server I have to assume its Redis inspired.
Now the curious question is whether it provides some different feature, its a learning exercise or something else.