Physical to Virtual is referring back to Physical Clones, 2 sections back on the same page. This page contains the first mentions of physically cloning drives, then when expanding on the topic appears to berate the user for not understanding the material.
I’m pretty sure this book is AI slop. There are several instances where the material is just thrown onto the page and not properly organized.
Honestly read the Proxmox Wiki
It is actually pretty good
I am actually focusing on getting my server plus, so while it would be helpful, it might be focused on a single aspect.