Actually, I do think Master of Lore would be broken if the errata was removed.
Out of the Wild (OotW) can become free because Master of Lore reduces the cost to 2, then secrecy reduces the cost to 0.
With 4 Lore heroes Scroll of Isildur is also free. So if your deck is empty you can play OotW -> Scroll -> OotW -> Draw -> OotW -> Second Breakfast-> Scroll -> OotW -> Draw -> OotW
That's 5 OotW for the cost of 1 resource (2nd breakfast) and 2 card draw (each card draw is worth ~1/3 resource with Mithrandir's advice (which takes one card to draw 4 cards for a gain of 3 at the cost of 1 resource)) for a total of 1.66 resources. You can repeat this 3 times before you need a Will of the West, allowing you to remove 15 cards for 5 resources. Then Will of the West for 1, and draw 9 cards (costs 3). We are now at a total of 9 resources spent to get back to where we started. You need to do this ~3.5 times to kill an encounter deck. That means the total cost to remove the encounter deck from the game is around 30 resources plus setup costs. It's expensive, but not hard to do with people cooperating with Legacy of Numenor and Parting gifts, etc.