We provide standard ways to connect to databases outside the application container, like Running Discourse with a separate PostgreSQL server. The details of networking on those advanced setups are up to you, since it will be wildly different depending on your implementation.
We already gives a dead simple install for everyone on https://github.com/discourse/discourse/blob/master/docs/INSTALL-cloud.md that works and power thousands of instances in the internet. I’m afraid that those who opt into following their own path will have to deal with the consequences as it is impossible for us to provide support for all the possible combinations.