Just to add to the pile of reasons: The Bitnami install is insecure, because it is outdated. Discourse has a good track record for security, but as with most software, this only means that you’re good if you keep up to date. As soon as you’re behind on commits that start with SECURITY:, you are at risk.
Maybe a Bitnami install is okay if you just want to evaluate Discourse privately, but as long as they haven’t figured out how to deliver updates promptly, I’d strongly urge anyone to keep Discourse Bitnami install off the internet.