Disregarding the smoke aspect, exposing the burner pot would give you the ability to sear.
From what I have read, Traeger was the first to develop the pellet grill, drawing on their experience from making wood pellet heaters, When their patents ran out, the pellet grill market opened up and many of the grills today, including the MM, were derived from Traeger's original design. The burner pot, auger arrangement, combustion fan, igniter rod, and the hopper assembly on the MM are very similar to the Traeger 700. How do I know this? I am building a DIY controller that was originally designed to fit the Traeger and in tweaking the design to fit the MM I'm finding just how similar they are.
Just for fun, here's a link to the controller OEM that is supplied with the MM. The company also makes other controllers and related hardware for other grills, including the Traeger and likely the MM.
Supplier kitchen accessories, oven lights, sensor, metal switches, knob switch, transformers, pulse igniter
jv-cn.com