Ridge vents without baffles / barrier flanges that protect the air openings can become plugged with blowing snow which will reduce their venting effictiveness.
The fiber mesh ridge venting material under this asphalt ridge cap has been rendered practically useless after being crushed by roofers nailing with nail guns. Fiber mesh ridge venting is not very efficient to begin with, but, to work at all it needs to be installed by carefully hand nailing with long roofing nails to prevent closing off the venting space.