What is your basis for your opinion ?
How many people have you shot, seen shot, treated for gunshot wounds etc ? I'm at 30 plus combined. BBI is likely well beyond that.
Like everything else, the truth is somewhere in the middle.
Handgun calibers matter up to the point you are into service caliber handgun rounds (9mm / 38 Special) that meet the FBI terminal ballistics testing standards (12-18" penetration in ordnance gel).
You get what you get in a fight, life is not fair. If al you get is a foot, shoot the foot. The difference between shooting a guy in the foot with a 45/10mm/40 and shooting them in the foot with a 9mm/38 is inconsequential.
The mirror image of what you are talking about is the people who believe a more powerful round will make up for poor shot placement. We see this locally with hunters who never practice marksmanship trying to make up for incompetence by shooting 130 lb deer with 7mm mags, which ironically reduces competence even further.