I'm not sure I can switch. I have too many friends linked to my server and a decade-ish of watched data.
I know many people watch from TV apps and Chromecasts and I don't know if there's an app for every TV brand for jellyfin or emby or whatever.
People watch from all sorts of weird devices. I got push back when I forced SSL because at least one person had a TV so old that it didn't support doing SSL for Plex. It took me a week to drill it into their brain that I'm not going to change it back and to go buy literally anything to make it work (Chromecast type thing). I think their ended up buying a Roku.
This is just the brainpower that most of the people I share with, have. They just want easy. I do all the hard work in the background and their life is easy.
I can't imagine how many would have a fit if I forced them off Plex. Jellyfin looks cool and all, but it's unlikely I'll be able to move anytime soon.