Definitely performance. Writes without a transaction are slow. SQLite's 99.999% use-case is for single thread single access, so you lose little and gain a lot by deferring writes until you actually need them done.

> I'm not sure if I would want my database to commit multi-query transactions without an explicit command to do so.

You can easily disable it by setting the isolation level per https://docs.python.org/3/library/sqlite3.html#controlling-t...