There is already an existing Corruption or Crimson Thread. Your Thread has been merged into the already existing thread.Personally I think they both have their pros and cons. For example, from my experience Ichor flasks seem to do much better against bosses and enemies than Cursed flasks do. Than again, Corruption drops the chain guillotines which is one of my favorite weapons. Than againnn, Crimson biome chests have vampire knives which is also one of my favorite weapons.
As a tip for the future when creating threads, its a good practice to to use the search function at the top right to see if your thread idea already exists or not. If it does it is fine to post on the old thread. We don't allow duplicate threads as a forum policy so posting on older threads to revive the discussion is better than creating new threads for the same topic.