My DA/SA semi-autos one can remove the mag and the gun won't fire. So load the gun and after racking the slide(safety off) you are cocked and ready to fire then eject the mag.
No I wouldn't carry cocked with safety off but I would leave a gun in the condition I described for short periods as long as I'm in possession of the mag.
So I purchased both guns one NIB tried both to assure the mag disconnect did function yet I'm to still disregard it as a safety? You do know S&W used the mag disconnect as a "safety" feature in their advertising? Bubbafied guns are a risk on the used gun market and something I avoid like the plague but I'm also not in the habit of picking strange guns and just pulling the trigger either.
In the context of all of your posts, the earlier ones being the ones I was referencing, yes, I believe what you said you thought was OK is a really bad idea, chambering a round, removing the mag, and leaving the gun and assuming its "safe". I cant figure out a good reason to do so, and certainly wouldn't regard the gun as safe sitting around out of my direct control.
YOU may not pick up some random gun and pull the trigger, but others may. Besides the issue that something like a magazine disconnect could fail, its also pretty easily overcome. A pen, pencil or other object stuck into the mag well can raise the disconnect lever in S&Ws and the gun fire. As a last ditch to keep from getting shot with your own gun in a disarm, or around poorly trained people that aren't very smart about what they do with their guns and don't completely comprehend how to unload a pistol*, they have some value. As a "safety" to keep the gun from being fired when left chamber loaded and unattended, NO, I don't think its a good idea, at all.
*It apparently isn't all that unknown for people in the .mil to "unload" their pistol coming into unloaded zones to eject the round from the chamber, then remove the magazine (to unload it), then snap the gun in the safe barrel to prove unloaded (another really poor idea I believe), and are surprised when the loud noise happens.