Comment by gr3ml1n

SFT can be used to give negative feedback/examples. That's one of the lesser-known benefits/tricks of system messages. E.g:

  System: You are a helpful chatbot.
  User: What is 1+1?
  Assistant: 2.

And

  System: You are terrible at math.
  User: What is 1+1?
  Assistant: 0.