What does a car do that you can't trivially do with something else ? Like a boat or an airplane ?
You simply cannot compare an in-memory Key-Value store, to a RDBS. And that's on a conceptual level. If you then consider performance, network latency and the guarantees, we're absolutely comparing airplanes to donkeys: You wouldn't use an airplane to climb up a rough mountain, and you certainly wouldn't prefer a donkey to travel to the other side of the world.
On the other hand Redis is a bad database so I would say the use cases don't overlap.
SQLite supports atomic operations - the key requirement of a message queue.
All this to say that, yes, you theoretically CAN use SQLite as a message queue. But atomic operations are usually WAY lower on the "must have" list for a message queue than other parameters.
The easiest way you could verify this is by looking at the guarantees provided by some of the most known MsgQueues.
This is what ensures only one reader gets a message. SQLite has it, redis does not.
That is a claim not an argument, and again it can't be a shared queue because no networking.
Or do you believe Redis doesn't have atomic operations?