The ‘element of surprise’ is an offensive tactic, not a defensive tactic. If you surprise an attacker with a hidden gun, that’s called “damage control”, not surprise.
Call it damage control if you like, it CAN be a defensive tactic and sometimes it's a lifesaver.
A real world example was posted on THR some time ago. It was a situation where a disturbed man took the employees of a shooting range/gun shop hostage. He came into the shop & looked around for awhile, rented a carbine and went to shoot on the range. He loaded the gun on the range and then returned to the gunshop area with the loaded gun and got the drop on the employees before any of them could respond.
Later in the scenario, the gunman herded the employees out into the alley and made it plain he was going to kill them. At that point the only employee who was carrying was able to draw from concealment, taking the gunman by surprise and incapacitating him with several shots. Only the criminal was wounded.
Had the employee been carrying openly he would obviously have been disarmed or shot immediately given that the gunman carefully observed the situation for some time before making his move.
The employee's actions were CLEARLY defensive and yet the element of surprise was critical to his success. His ability to CHOOSE when to respond, his ability to be armed without the gunman knowing he was armed, was INVALUABLE in that real world situation.
I researched armed self defense scenarios some time ago and found several in which the defender's concealed gun was used to surprise the attacker and turn the tables. One was another hostage situation in which a man and his wife were taken captive and driven some distance in their own vehicle before they were able to retrieve a concealed gun and end the situation without being injured.
Is it a factor in every scenario? No, it would be foolish to pretend it is.
On the other hand it IS a factor in some scenarios and it's equally foolish to pretend it is not.
I'm not against open carry and I've posted to that effect more than once. It's not an option that I would use in public very often, but I think that it should continue to be allowed where it's already legal and should be legalized where it's not. However, there are some disadvantages that go along with the advantages provided by open carry. Any reasonable evaluation of the facts will make this clear.
In my opinion, the fact that OC supporters on the internet virtually always exaggerate the advantages of OC while trying to
completely dismiss the disadvantages is one reason that many people find it hard to take them seriously.