Why? It’s an electric oven. That oven can actually be operated without being under a kitchen hood.
The only duct within this oven would be one within the TOP oven of a stacked set is to facilitate ventilation of the the lower oven’s blower motor. THAT little duct would be included in a stacking kit – item 1 in the photo. Item 3 is merely the top cap for venting air for the TOP oven’s motor. Its true reason for being there is to keep things set on top the oven from falling down into the motor section – which kitchen staff would most CERTAINLY do.