Usually and I do agree, but I and many others have shot and witnessed many animals hit with most every type of hunting caliber and some gave little to no indication of a hit. I've seen 120# whitetail does break and run from chest hits from 270's, 30-06's to 444 Marlins and 12ga slugs that ran as if nothing had happened. And then I have seen several fall DRT from a 222 or 223.Impact velocity seems to contribute significantly to an animal's visible reaction to the shot. I hit whitetails in the chest with a 50cal ML that didn't immediately react, and some got quite far despite a massive hole in their lungs. Most high velocity rounds elicited an immediate visible reaction to the impact. "Most" but certainly not all.
I've seen elk absorb multiple impacts from 300's, 338's and other only to trot over the top, into the valley or thickets as if nothing had happened.
Defensive handgun situs against dangerous game are rather last ditch choices, and since velocities are not the highest with most of these weapons, bullet diameter and penetration (momentum) are key factors to increasing one's odds of winning the fight and surviving. Big bears, like other large animals, can absorb a fair amount of punishment and keep raging, especially if the vitals and bones are not sufficiently reached and transversed. The bigger and deeper the hole, the more and faster the blood loss and trauma inflicted.
Personally, I am not a fan of large capacity mags for bears, for rarely, will one have time to mag dump a dozen or more rounds before he is on you, has thought better of the situ or is down. However, most people will never need to actually shoot a charging bear, so if a large cap mag ads to one's confidence, then by all means carry. Whatever caliber/cartridge/weapon one chooses, become proficient at using it and in a fast, high stress situ.