I host a Plex server for close to 70 friends and family members, from multiple parts of the world. I have over 60TBs of movies, tv shows, anime, anime movies, and flac music, and everyone can connect directly to my server via my reverse proxy and my public IPs. This works on their phones, their tvs, their tablets and PCs. I have people of all ages using my server, from very young kids to very old grandparents of friends. I have friends who share their accounts with their families, meaning I probably have already hit 100+ people using my server. Everyone is able to request whatever they want through overseerr with their Plex account, and everything shows up pretty instantly as soon as it is found and downloaded. It works almost flawlessly, whether locally or remotely, from anywhere in the world. I myself don't even reside in the same home that my Plex server resides. I paid for my lifetime pass over 10 years ago.

Can you guarantee that I can move over to jellyfin and that every single person currently using my Plex server will continue having the same level of experience and quality of life that they're having with my Plex server currently? Because if you can't, you just answered your own question. Sometimes we self host things for ourselves and we can deal with some pains, but sometimes we require something that works for more people than just us, and that's when we have to make compromises. Plex is not perfect, and is actively becoming enshittified, but I can't simply dump it and replace it with something very much meant for local or single person use rather than actively serving tens to hundreds of people off a server built with OTC components.