It's a simple fact of life that you're going to inevitably break the muzzle-crossing rule
anytime you carry, no matter what carry style you choose.
That's where smart holster design comes in! Check out this classic thumbreak 1911 holster, which was literally the first Google result:
Now, if you're not familiar with 1911-pattern pistols, they (mostly) have very light single-action triggers, usually with no travel.
They've also got two safety mechanisms. The first is a manual thumb-operated safety located on the side of the frame, which blocks movement of the sear/hammer arrangement (and locks the slide closed when activated). The other is a grip-activated safety located at the backstrap, which blocks the trigger bow from moving backwards and pushing on the sear (by way of the disconnector) until it's deactivated.
Now, both of these safeties can fail relatively easy in carry conditions. The grip safety (which doesn't block the hammer/sear anyway) is easy to accidentally deactivate. And the thumb safety gets deactivated all the time, on holstering, by movement, etc.
But the thumb-break holster guards against all of that. In Condition One carry (round chambered, hammer cocked, thumb safety activated) the leather band that snaps around the gun to secure it
also blocks hammer from striking the firing pin. In other words, every mechanical safety on the gun, plus the hammer and sear, can fail simultaneously, and the holster itself will prevent the gun from discharging.
But rather ingeniously, if you need the gun in a hurry, simply grip and pull hard enough, and the snap pops right off (assuming your belt actually fits).
Now let's take a a look at a pocket holster for an S&W J-frame:
In contrast to the 1911, the J-frame has no safety devices. All it's got is a heavy double-action-only trigger with a long pull. The hammer rests against the firing pin (on later models with frame-mounted pins), on a loaded chamber. And since the hammer is internal, there's no way to secure it from the outside.
That's where the pocket holster comes in. By completely covering the triggerguard with firm leather, Kydex, or other sufficiently stiff material, there's no way to actually work the trigger.
The only time you can actually work an object, like an errant pen or a drawstring, into the triggerguard with enough force to fire the gun, is on holstering. That's why the typical practice for pocket carry is to first insert the gun into the holster, and
then insert the holster into the pocket. And that's also why smart practice with any gun is to holster slowly.
Don't think of the gun alone. The holster itself is a safety device, which is another good reason not to cheap out on one. Good holsters are great, inexpensive holsters are fine, and cheap holsters get you a hole in the foot.
I also find it mildly interesting to study how different carry options work with different handguns. It's a lot harder to distrust something when you don't understand how it works.
And it goes without saying that if you're just dropping your revolver in your pocket, you're doing it wrong.