Nobody does 4 until they’ve had multiple large incidents involving DBs, or the spend gets hilariously out of control.
Then they hire DBREs because they think DBA sounds antiquated, who then enter a hellscape of knowing exactly what the root issues are (poorly-designed schemata, unperformant queries, and applications without proper backoff and graceful degradation), and being utterly unable to convince management of this (“what if we switched to $SOME_DBAAS? That would fix it, right?”).
Then they hire DBREs because they think DBA sounds antiquated, who then enter a hellscape of knowing exactly what the root issues are (poorly-designed schemata, unperformant queries, and applications without proper backoff and graceful degradation), and being utterly unable to convince management of this (“what if we switched to $SOME_DBAAS? That would fix it, right?”).