There are several things that have not been addressed . . .
When you say leave it loaded - are you talking about after you have already shot it? If so, then no . . . unless you waant a pile of rust the next time you go to use it.
If you are talking about leaving a "clean" revolver loaded - then yes. But I would also ask "why"? If you aren't going to use it for an extended time, empty it and clean it.
A C & B is no different than any other firearm. It is your responsibility to know where you weapon is at all times and just for safety issues, why leave a loaded one around? Are you going to lock it up so nobody has access toit? Are there kids around? And believe it or not, I can remember of at least two shooting deaths which involved a cap and ball revolver that was loaded and kids getting their hands on it. Just because it is uncapped doesn't mean that someone playing around with it (kids) won't try putting a paper cap on it and trying to snap it. Or . . . prevent them from finding percussion caps and playiing with it.
i.e. - it all depends on your circumstances. I carry CCW and yes, my carry weapon is loaded (cartridge but it still applies to C & B) and I know at all times where my weapon is and that it is under my control. However, if that weapon is going to be put in a drawer or a storage cabinet, it is unloaded and separate from the ammunition. It's just common sense. And in the last 60 + years that I have been shooting BP as well as cartridge, I have seen individuals who have put loaded ML away loaded, only to take them out months later and they forgot that they had put them away that way. Yea, you can see the loaded chambers on a C & B but why take a chance on a potential accident happening? A few minutes of time and you can be sure that the weapon is empty and secure - a few minutes of laziness in not securing it properly can result in something that can't be undone.
Call me an old fart and criticize me if you must . . . but I have seen the results of just what we are talking about here as far as safety goes when I worked Fire Rescue . . . . and what I have seen has caused many, many sleepless nights.