Jellyfish cannot to setup to securely and safely be exposed to the Internet. It is only safe to access through a VPN. That rules it out as an option for sharing with friends, family, or even my own spouse. You call it phoning home to the mother ship; I call it paying Plex to manage user authentication for me. Until Jellyfin's security holes are patched and it becomes clear that the Jellyfin developers actually care about security, it stays locked down to my LAN. Setting up a VPN is difficult for the average user on a good day, impossible in some circumstances on even the best of days, and is not access I want to hand out (and support) to all the people I share my Plex with anyway.

Not really true for self hosting a media library though, as this all relies on indexers, torrent sites, Usenet providers, metadata providers, subtitle providers, etc. If you host it for others outside of your household, you also rely on your ISP, their ISP, etc.