Trivial deployment model, can avoid owning/managing your own server, easier coding in the sense that no-network means you can do normally-psychotic things like N+1 queries and single-row inserts and get away with it.
SQLite/DuckDB actually enables a bunch of normally-illegal behavior when you compare to normal databases. Backups is just copy&paste of a file; spamming queries willy-nilly becomes cheap; you can version the whole DB in git (can’t diff it properly.. but you can do cross-db queries with SQLite ATTACH); locking concerns goes out the window because it’s single-writer anyways.
But if I were actively trying to support multiple users with a single source of truth, I’d probably default to Postgres. If it’s single-user, default to SQLite/DuckDB. If it’s single-user with multiple devices, default to SQLite + replication.
