https://permazen.io/ exists and is a simpler yet still very powerful way to think about databases (for java but the concepts are general).

But it's only really efficient if it can run code right next to the data via fast access - ideally the same machine. The moment you have a DB running on separate hardware or far away from the client, it's going to be slower.

SQL is a very compact way to communicate what you want from a complex database in a way that can be statically analyzed and dynamically optimized. It's also sandboxable. Not so easily to replace.