For me at least, putting the magazine and ammunition somewhere else, even if it is in the same room but on another table or something, is a fail safe just in case I have an inattentive moment. I actually HAVE experienced an ND. ONE. With a .44 magnum inside my bedroom. It scared me into absolute compliance with safety rules ever since. I have no problem admitting that my ND happened because I was distracted and did not pay sufficient attention to whether or not the gun was fully unloaded.....it still had one round in the cylinder, and the 5 that I had dumped into my hand looked like 6. It was a stupid, Stupid, STUPID mistake that I'll never repeat again. I had just dumped the 5 rounds on the bed next to me. If I had taken the time to get up and go set them down somewhere else, I might have had a second opportunity to notice that it was only 5, and not the 6 I thought I was holding when I set them down.
My answer to why ought one separate the ammunition from the gun by enough distance to eliminate a problem is say that the question is akin to asking "why do you rack the slide more than once and then visually and with a finger inspect it to make sure the gun is clear?" The answer is: "we do it more than once and then confirm that the chamber is clear with our eyes and our finger, because it only takes a couple of seconds, and it double, triple, and quadruple checks that the gun is clear. Then nobody accidentally shoots himself, his wife, his child, or one of his grandkids.
Until you've actually experienced an ND (and I hope you never do), you can't possibly know how horrifying those first seconds are until you can confirm that you've not shot yourself or anyone else. God help you if you have shot someone.
