[kantselovich]

If there is no database, where one should persist state?

Most software is stateful and needs to persist state across restarts, so I would argue that one needs at least SQLite.

On SQLite being safe default: in practice it means supporting multiple databases, say SQLite and Postgres, this is more complicated that supporting just Postgres. As soon as a project leaves localhost and enters cloud development you need talk to a database over network, which warrants MySQL or Postgres.

Which is more complicated: supporting a docker container with mysql or Postgres for local development OR supporting multiple databases in the project?

Of course, the answer could be “it depends”, I but I would not call SQLite a default choice. It would be if you are writing desktop or mobile app, but for anything like a web app it’s a questionable choice.