Not all contests allow unrated participation, but sometimes I just want to take part without worrying about my rating. Having an unrated option would encourage learning and experimentation, especially for participants who want to practice in a real contest environment without pressure. Moreover, this could help reduce cheating: people who only want to participate for fun or practice could choose the unrated option,while those who cheat would be less motivated to affect rated standings. In short,every contest should offer an unrated participation option.