I don’t know why but figured the same as you. If they bothered to document it, I’d bother to follow it. I did the download only option too since I also run opnsense from a VM.

I don’t see why this needs to be mandated. If users want it, it will be made

I run proxmox so I have a VM dedicate to HA OS with frequent backups. This allows me to also run a number of other things without worrying about inadvertently messing up my HA install