The amount of care people give to their barrel while cleaning is directly proportionate to how long the barrel will shoot well.
I don't care if they wreck a barrel by using junk cleaning rods or by buggering up the crown of their barrel, or wrecking the throat of their barrel...after all it is their barrel to wreck. I want my rifles to shoot well for a long time, so I tend to be gentle on them, and careful when cleaning them.
Most of the cleaning I do with AR15's concentrates on getting all the unburned powder, and carbon out of the upper receiver. The actual bore of the rifle is the last thing I clean, and takes the least time, but I use a one piece cleaning rod, and bore guide to protect the throat, and crown of the barrel.
I do NOT push the bore brush all the way through the barrel, then drag it back into the barrel over the crown as that can prematurely wear out the bottom of the crown of the barrel. Like I said, what other folks do with their barrels is their business and doesn't concern me.