I can say the same for my UDS, but if the blower is not raising the temp, then it's underpowered. Unless he has so much ash build up that it is blocking the inlet.
I have perfect control of my UDS without a blower, if I set the inlet valve correctly(my weber lid is always open all the way) and start enough coals, I can hold a steady temp all day and night, without touching it. But, If I put my blower on it and I don't correctly set the blower speed, then my UDS won't hold temp and will drop below 200.
Looking at his graph while he was smoking, I can tell the blower, in this case, a fan was either underpowered, inlet was plugged up or outlet was closed down way to much.