Went through LEO Basic in 1976. We carried Model 10's (nickel) and drop pouches. This is how we were trained to load (for right handers). Drop pouch on right side of duty belt. Hold the revolver in left hand with two middle fingers around cylinder (see picture). Use thumb to eject empty casings and to turn cylinder while loading bullets with right hand. Keep muzzle pointed downward and down range with left shoulder pointed towards target (standing sideways to target) makes yourself a smaller target. During qualification we had six in revolver, twelve in drop pouches and the remainder in right pants pocket. Holding the revolver this way you are less likely to drop it and harder for a bad guy to take it away. Have seen many folks load revolvers all sorts of ways. Recently took my nephew and brother to range. Nephew never shot a revolver and brother very rarely. Taught them this method. Still use this method after all these years!
The problem is three fold.
First, in order to use gravity to your advantage you need to have the muzzle pointed down, and in this position you are already virtually in a wrist lock. The assailant just has to grab it by the grip and then twist it towards himself. You'll be forced down and forward by the resulting wrist lock, or you'll release the weapon. You lose either way.
Second, in order to keep the revolver close to vertical, you have to lean forward. Between that, and needing to individually load each round in the cylinder, it's virtually impossible to keep your eye on the assailant and maintain situational awareness. The officer shot in the Newhall shooting during the reload was killed as much or more by the loss of situational awareness as he was by the slow reload.
Third, holding a revolver that way works well enough with .38 Special, but 6 or 7 rounds of .357 Magnum will leave the forcing cone hot enough to burn your middle finger when held that way. Officers have indeed dropped their service revolvers for exactly that reason.
The loss of SA and the potential for putting yourself at risk of a wrist lock were two of the primary reasons for the Stress Fire Reload with the hot forcing cone issue encountered in the FBI and Universal reloads running a tight third. In the Stress Fire reload, you hold the gun vertically and hold the cylinder open with the thumb on your right hand between the cylinder and frame while striking the ejector rod with your left hand. It ensures a straight shot on the ejector rod with no finger in the way to shorten the stroke.
You then place the revolver muzzle down in your left hand, with the thumb wrapped around the ejector rod to keep the cylinder open and the revolver supported on the other side by your fingers. This eliminates the near wrist lock position and allows you to keep your head up and your eyes on the assailant.
It also assumes the use of a speed loader, but it also works (slower) with a speed strip.
Loading single rounds in any manner will require hand eye coordination that requires you to look down at the cylinder and lose situational awareness.
Feel free to load anyway you like but God help you if you ever need to load single rounds in a fight.