Not even a decade ago we were hosting our web-facing services and our postgres DB on the same server. A lot of smaller projects had their own db and credentials

Not even a decade ago we were hosting our web-facing services and our postgres DB on the same server. A lot of smaller projects had their own db and credentials on the same instance. The idea of having to spin up independent DB servers for each one seemed wasteful to us, since back then each box would cost at least £10/mo or more on Linode or Rackspace and it meant more secrets to keep, more stuff to secure, more stuff to maintain. It was only with the advent of heroku and the sudden shift to the cloud (AWS) that the DB stopped being software you ran on your box as a daemon, and became essentially a dedicated resource. Even for services running at a completely trivial scale.