Multiple of my friends, my family and I have stopped playing terraria because of the immense amount off work blocking off the evil biomes requires and we all agree on this idea. It would work by adding a switch in the creat a world page that could turn off the spread of evil biome like the hollow, crimson, and corruption. This would be a great addition to the game because if you did want the spread of evil biomes you could just leave them on and if you didn't want to spend time blocking off those evil biomes you could just turn it off. As a side note adding it to all platforms would be great.