On WSM, UDS, etc. you are correct. However, on a Kamado, the top vent is used to control temps as well. With your Vision Kamado, you will have a tough (and may never) get down to smoking temps leaving the top vent wide open.
For example, I am cooking a butt on my Chargriller Kamado today at 275*F. I have both the bottom and top vents cracked about 1/16" and am purring along nicely.
A nation of sheep will soon have a government of wolves - Edward R. Murrow