That has more to do with TheTVDB than with Plex itself, and it's really nothing compared to what Jellyfin demands. Plex at least supports several different alternative directory structures and file naming schemes. In order to transition to Jellyfin I would have to rename thousands of files to comply to its specific requirements, whereas Plex was mostly okay with the way I had organized my files offline.

Plex hasn't bothered to work on this in 15 years. It's been the same since I was in college and I'm almost 40.