There are many hot-button topics that have passionate people on each side. This is one of them.
In the history of firearms development some bad things have happened. These bad things have cemented some best practices that are no longer relevant since firearms manufactures learn and improve.
One of these best practices is to never have a live round under the hammer/firing pin/striker. This was important when firearms did not prevent inadvertent discharges when a gun was dropped, or the hammer was struck. Modern firearms are much less prone to these issues. Note that I said less. It is not an absolute as the U.S. Army found with their new duty sidearm. It has a specific set of circumstances where it will discharge when dropped. You must know your firearm!
That being said, the one in the pipe carry is a matter of personal choice and carry conditions.
Let’s first address the carry condition. If you throw your carry gun in your pocket (or purse) without a holster you should not have a round in the chamber or under the hammer. A revolver (Uncocked, of course.) is safer than a semi-automatic but you are still taking a risk. Is there anything else in the pocket or purse that could engage the trigger? When you retrieve your gun are you 100% certain you will not engage the trigger? There is no way you should accept that risk. Either do not have a live round in the chamber or use a pocket holster that covers the trigger.
Now for the personal choice.
When a firearm is carried with a live round in the chamber it is only a step (or two with a safety) away from discharging. That condition may be more that you are comfortable with. If it is, then don’t carry with a live round in the chamber.
If it is so close to discharging why would anyone carry in that condition?
The first issue is time. It takes only seconds to rack a slide. However, it takes only seconds for a threat to close the distance to you and inflict injury. The question you need to consider is are there more seconds between you and the threat than you need to draw, rack the slide and fire than it takes for the treat to get to you.
Another consideration is noise. If you are not the primary focus of the threat racking the slide may cause the threat to refocus on you.