[Tx Firefighter]

Early engines didn't use PCV either. They used a thing called a "road draft tube" that used the air moving under the car to evacuate the gasses. Mainly, emissions requirements caused the widespread use of PCV. It just wasn't environmentally friendly to let those fumes go into the atmosphere. With the PCV, they get burned. This is one of the few emissions devices that work well, and are helpful to the health of your engine.