I'd say it's also to stop people from doing dumb things (i.e. proactive defense).

Say, if the org runs Postgres in-house, there's a mighty chance that an intern somewhere might decide to ...test things out in a creative way.

Perhaps the idea of outsourcing that to Oracle is that Oracle has the processes/controls to rein in such interns. As opposed to e.g. a hospital having to create such processes/controls.

(Oracle is still a bad idea IMHO, just slightly less so comparatively)