When you get into trouble you may loose video. You'll never find it in the sky when you remove your goggles.
Also the FAA requires line of sight flying.
You mean the AMA.
The Line Of Sight thing comes from the AMA.
Trying walking around your home with side blinders on. You're constantly turning your head to "path plan".
FPV cameras only have a usable 60deg view. For multicopters which are omnidirectional--that can be a problem.
no idea who the ama , in nz we are a bit more relaxed on rules, our version of the faa in nz are idiots so no need to fear them
Roll of spotter:
This being said, I don't always use spotters, but I usually have someone with me to help read way-points or just watch my back when flying.