Generally I'd agree with you - I do use Docker containers for a few other things, but find Emby well-behaved enough to not interfere with other things the host is doing. If that ever changed, I would definitely containerize it.
On a side note, I have a habit of installing an OS once and never again (even Windows on my PCs). I spend too much time tweaking and customizing things to ever want to do it again from scratch; that's what disk image backups are for, IMHO.