Most pistols and carbines with battery powered red dot sights have iron sights for use if the dot goes out.
Question: Has your dot ever gone out such that you had to finish shooting the gunfight, match, or regimented training with the iron sights?
A friend has no iron sights on his main gun used for match and carry. He figures that if the light fails, his well practiced index to see the dot immediately upon the draw will let him frame an assailant in the window well enough for drastic emergency defense.