What did we do BEFORE PCV systems? Before the mid 60's, not that many cars were using the PCV system and the engines were just vented to atmosphere via a down tube (draft tube).
Yeh....BUT a draft tube is much different than open breathers throwing oil all over the firewall, and THEY DID ANYWAY!!
I still remember some of those days, and the "local oil burners." You could always tell "Smittys" 50 Chiv wobbling down the road because it had a blue trail enshrouding "the rest of us." And you could "goose" the engine with the hood up and see a puff of oil smoke coming out the breather, adding to the dusty, oily, greasy "stuff' all over everything.