I also believe you should always have your weapon chambered but I think this person may be asking from a safety point of view considering all the accidental discharge stories associated with glocks. I carry a gen 2 glock 22 and feel safe but that is in a good holster with the trigger covered and tons of practice. For a beginner, I would suggest they use a pistol with a grip and trigger safety until they reach a confidence level that allows them to feel safe chambering a glock. Lack of training, a cheap holster with access to the trigger and gittery nerves have caused more than one person to shoot themselves going for their glock.
True statement, training is needed to carry any firearm, not just a permit as this does not make you proficient in handling a firearm. I first carried my G22 around the house for about 3 months with a empty mag and clear pipe until I was comfortable drawing from my holster and re-holstering it. Then I practiced with a full mag but still nothing in the chamber and racking the slide with both hands and one handed. Then I felt confident enough to carry with one in the chamber.
As for the accidental discharges I personally think that is a excuse, it should be listed as a negligent discharge. From everything I have read or experienced, a Glock will not fire with out something hitting the bang switch, either a finger, worn out holster edge, car keys, something in the trigger guard has to depress the safety and trigger. To me this is negligence, I may be wrong but that is just my opinion.
With that said a great gun needs good equipment, a good quality holster and gun belt will go a long way to help keep you safe.