As a Jellyfin-fanboy: you are right. Plex is easier to deal with out of the box.
Anything else would not make any sense for a paid service.

I’d say though, if you dedicate the time to set it up correctly, it is an equally good solution and it’s free.
If time is a factor in your life, then there is no shame in paying for something that just works. It’s why I have a Synology NAS and not a self-built Unraid or OMV server.

I run Jellyfin on Chromecast with Google TV every day, it works super well.

Unless you mean casting from your phone, then I don’t know.

The ability to watch from anywhere.

Install on the Jellyfin server and share that server (or just the IP with the Jellyfin port) with whoever you want. Now they have access to Jellyfin and Jellyfin only.
That’s how I set stuff up for friends and family.