Well, I read the thread, and this is my conclusion about tacking. I've probably prevented three armed robberies about to take place in a Kentucky Fried Chicken, a gun store and a stop-n-rob convenience store. Also an assault from the rear in a WalMart restroom. I say probably because all four potential incidents never actually went down, so I have to qualify my statement.
Okay, so what you are saying is that you read the whole thread, finally, and still completely missed the points being made. Shooting isn't always an option and is no option if you don't have a gun. So what are you going to do if you aren't armed or can't use your gun if you find yourself in an active shooter situation? By active shooter, I am not talking about your unrelated stories of stopping robberies that never occurred. Those were not active shooter events and hence are in no way related to the thread.
Just because you are unarmed or can't use your gun should not mean that you are defenseless or helpless, though being defenseless and helpless is how many CCW folks describe themselves on forums like TFL when they talk about being unarmed. There are options, all sorts, and if you want to take an active roll in stopping the shooter, tackling is an option that is often used successfully. It is done at great peril, no doubt, but chances are the folks in the situation where the active shooter is killing people are already in great peril.