Why a compound of iodine should not be added to sodium chloride used in food

I think this question is wrong.

I can name at least one case where a compound of Iodine is added to sodium chloride used in food and with positive results.

This is the case of potassium iodide or calcium iodate added to common salt (sodium chloride). This is done in many countries as a medium to satisfies the need of Iodine of the organism.

You could think that some free Iodine could react with sodium chloride, displacing the chloride but this not happen because Iodine is less reactive than chloride.