As said in literally every thread here that ever mentions anything about Plex or jellyfin, biggest is remote library sharing.

No, I will not walk my in-laws through setting up a vpn gateway so their TV will connect to me

No, despite my extensive homelab setup, I am not going to set up a reverse proxy and go through the SSL/TLS cert bullshit and expose especially considering the security limitations the devs say likely will not be fixed

There’s others, but those are the main ones for a bunch of us