Not that I want to defend Plex which is definitely enshittifying, but I don’t think most people are buying Plex to stream their own media. They’re doing it so other people can stream their media. Not wanting to buy a domain and set up port forwarding or a reverse proxy or whatever doesn’t seem unreasonable to me. My grandparents are never going to use Tailscale, and even if they did, I don’t think there are any Tailscale smart TV apps.

Disclosure: I run Plex and Jellyfin (and Navidrome) in parallel, and bought a lifetime pass years ago.