Years ago we used to tease a guy in our incubator about using SQLite in production. Who knew he was just ahead of the curve…
It's just a default that's being in Rails for a very long time. This let's you start a project quickly. And now the improvements to SQLite is Rails means it's also good to go for a production setup.
They’re not suggesting you use SqLite for your primary database but rather separate databases for caching and job queues. It allows you to drop redis as a dependency.