It sounds like maybe you are aware of how silly your argument is now: the fact that these happen to arbitrarily share a common word in English, does not make them a substitute for each other. If you still don't understand, you should try sautéing some shallots in peanut butter.

Edit: this is clearly different from a company marketing a product alternative, such as margarine (for butter) or Impossible Burgers (for ground beef).