I hear this from my buddies regularly. I understand that sentiment, but I practice unholstering, chambering a round, and firing every time I am at the range.
I'd wager to bet that I am faster pulling my pistol, chambering, and firing my firearm faster than most people that carry can unholster. It is personal preference, but I feel safer from accidental discharge (TWSS) without one in the chamber. I shot competitions when I was younger and I was always taught to never chamber a firearm until you are ready to fire downrange, that has always stuck with me. An "accident" cannot happen if a round isn't in the chamber.
Again, that was a personal choice of mine, so I fully understand carrying chambered is preferred for most people.