Its helpful knowing there is a large user community that utilizes Discourse. But it does remind me of a Monty Python skit where they build a block of flats that include a hallway of rotating knives-- “don’t worry you’ll be fine. Others have bought this same home and we have not received a single complaint.” I wonder why? 
I get the overall architecture with the Docker container, Ruby, PostgresSQL, and only one port exposed by default (80). However, I’m thinking out of those thousands of customers, I can’t be the first to be concerned about understanding the security issues surrounding Discourse.