Because traditional authoritative sources that I would look to for guidance are completely out of date. From where I sit it looks to me like they are more focused on milking endowments than discovering what is happening in the real world.
My take away was that the author doesn't necessarily claim to have all the answers here. It's more of a list of general guidance that is reverse engineered from the type of behavior the she observed was definitely unsuccessful.
Why are you writing authoritatively about something you know you don´t actually know then?