How common is Haki in the New World?

The strawhats trained for two whole years to be ready for the New World, and luffy, Zoro and Sanji all gained Haki. But how common is Haki in the New World? Haki is in every living thing and to be a Vice Admiral you have to have it, but what about new world level pirate captains? During the Whitebeard War 43 New World captains and Whitebeard's entire crew fought the marines and only Marco, Juzu, Vista, and Whitebeard used Haki during the war. Next you have the marines and pirates who fainted after Luffy used his Conqueror's Haki the marines had 10000 strong fighter. If the only way to beat a Logia without exploiting their weaknesses is with haki how are their pirates like brownbeard who was a New World pirate and didn't know Haki?