UEFI support is a replacement for the old-school BIOS; so that motherboard works alongside during boot. UEFI enables hardware trust for OS. So if OS detects someone plugs in something strange or non-compliant, it can react to secure the footprint of the devices. In use cases where Appliances will be sitting w/zero security so there’s concerns that when machine boots, all hell can break loose so having the trusted boot with UEFI would offer protection.