Imagine being a PvP designer in a meeting while planning the 8.3 patch and you say, "I don't think corruptions should be active in PvP -- it will screw up balance badly, and anyway it's really a detraction from the skill of using your abilities the right way and playing your class to its full potential when a huge portion of a player's damage will come from corruption effects and random procs that don't happen at a controlled time".
And then you get overruled by someone of a higher pay grade who pays zero attention to PvP because "corruptions are a core feature of the patch we shouldn't disable them in any content"