I agree with you on the CLI part. I tried Jellyfin once and it’s basically the same as browsing directories with movies in a file manager, for which you don’t need the whole heavyweight software stack.

I know Jellyfin also has transcoding and probably some even more exotic stuff, but even my phone can play full HD from SMB without transcoding, so I have no use case for these extra features.

Kodi is a good player on TV. Phones and tablets have VLC and MPV.

You mean the communities where the rules forbid asking newbie questions because people visit them to learn about new developments and inevitable FOSS dramas?