If overzealous means the same as careless, I agree. Letting the cleaning rod or pull-through accumulate a bunch of grit or rub against the throat or muzzle of the gun will likely damage areas that are critical to good accuracy. I suppose frequent use of abrasive or ammonia-laced bore cleaners could mess things up as well. If proper technique is used with the proper tools such as bore quides, I doubt that a lot of damage is inflicted regardless of frequency.
If overzealous means too often, meh, I don't think it hurts to keep the bore clean and the copper fouling to a minimum. I think the real message is to care enough to do the job right and don't substitute quantity for quality.