Also, I found that the only way to get obsidian without already having it is to make a pig iron sharpening kit. Most people don't find villages AND have enough materials to trade for emeralds/have enough villagers to make enough emeralds at the point that I am; and even fewer people find emeralds at the point that I am. Luckily I had emeralds that I found 10 minutes in, but that isn't most people.