Probably the number one recommendation I see in self hosting communities is to not open ports directly (other than for a reverse proxy). It seems like a common recommendation no matter the service. To be clear: I am a beginner. I know very little about this, but I've spent months learning. I can't say you're wrong, but I don't think you've made a convincing argument for me to actually understand why Jellyfin is unsafe to expose to the internet compared to any other service.