The soffit area need to be breathable to allow fresh air in. The fresh air is brought in through the soffit, and exhausted out through the vents located on the roof. In order for the soffit to allow the air to come in, it must not be covered, or blocked. In your attic is a system called baffels, which main operation is to position the insulation, and prevent it from covering the soffit area. Improper placement of the baffles, can result in problems with proper air flow. If you take a look in your attic, all the soffit area should be uncovered, and natural lights should be peeking through the holes.