There is no vent to atmosphere, by design. That small vent through the throttle body is all that is required. And venting this way has the added benefit of creating a net negative pressure in the crankcase which aids the oil seals, as well as reducing emissions. Which is why all the OEMs went to this type of set up in the 1960's.
From an engineering perspective, going back to atmospheric venting is a retrograde step.
