Blower and Damper?

I have an 18 and 22" weber smoker.
Usually I'm running a full smoker - keeping temps up is more of an issue than keeping them down.
I rarely use water in the pan.

I'm trying to figure out if you have good control/constriction to the blower (if it's not running, air is not freely flowing), why would you want to also control a damper?

I saw Ralph's graphs of his smoker, what a thing of beauty!

So, I figured there was something to it.

I figured that you could do as well just controlling airflow with the blower.

I'm really having a hard time wrapping my head around why I'd close the top vent - 2 instances come to mind - reduce overshoot/oscillation of the temps or to help hold the temps down when the blower is not running/reduce draft & convection effects??

Non insulated smokers like the WSM really bleed heat compared to a kamado type grill, so you naturally need to stoke your WSM more while a kamado needs to be choked down more. That said, my bullet smoker tends to ride a above 250F if I allow unrestricted flow through the blower, so the top vent needs to be choked down to reduce flow to land on the target temp. If you restrict the input flow with a damper you can then open the top vent more to allow a more controlled flow without choking stale smoke in the chambre.
If you are having no problem keeping temps low with your top vent open a bit and the HM is not sitting at 0% all the time then I see no need for a damper.

Thanks for the reply Ralph - makes perfect sense.