That is true, but I suspect that only happens to protect the zpool against tools like the Windows Repair Install (which likes to attempt repairs on disks withou

That is true, but I suspect that only happens to protect the zpool against tools like the Windows Repair Install (which likes to attempt repairs on disks without GPT label). Using ZFS on a partition inside a GPT disk tends to lead to a few quirky behaviours, like for example ZFS not always reporting correct SMART data of the device.