That breaks efficient code reading. When you read code, you tend to skip through basic-blocks (i.e. consecutive statements without branches) and follow them to that intersection point where a decision has to be made. In traditional form, if you have:

  if (condition) consequence();

You're able to "run" the condition in your head and step into the consequence without loss of pace. But when you put the consequence before the condition, you will have to backtrack.