My understanding/recollection of SQLite is that it has significant performance issues with high concurrency. Great for a database on a pocket device, not the best choice for a horizontal scale-out high-concurrency system. At what point do I need horizontal scalability, but not care about concurrency on any one node?
Again, honest question - I'm not doubting the project or its value, I just don't get it.
The goal is to create something more like an etcd that can hold structured data.
rqlite gives you the functionality of a rock solid, fault-tolerant, replicated relational database, but with very easy installation, deployment, and operation. With it you've got a lightweight and reliable distributed relational data store. Think etcd or Consul, but with relational data modelling also available.
You could use rqlite as part of a larger system, as a central store for some critical relational data, without having to run a heavier solution like MySQL.
rqlite replicates SQLite for fault-tolerance. It does not replicate it for performance. In fact performance is reduced somewhat due to the network round-trips.