"dedicated practice"
Aye, there's the rub. I tried pocket and string slings as a kid (10yo) and decided it was inaccurate --to the point of hitting myself on occasion.
Perhaps if I had kept at it for that whole summer vacation, I might have changed my mind. I went back to my Dennis the Menace (DtM) slingshot. Got fairly accurate with it, but the fact that nowadays they have DtM slingshots with laser sights on them should tell you something about their accuracy in "instinctive shooting" mode.
In later life I took up archery with a simple recurved bow and after I fixed sights and a kisser button to it, mere adjustments allowed me to hit paper plates at ~30 - 40 yards in short order and with excellent regularity.
This was before compound bows were popularized (or even invented.)
I think the deadliness and accuracy of the string slingshot is overestimated. Remember that David's (lucky?) shot happened to hit Goliath in the forehead, whereupon David had to go over and cut off Goliath's head anyhow.
Yeah, it's OK, if that's all you got --sort of like a .25ACP.
It would really take a down-and-dirty, no-holds-barred, me-stark-naked situation, for me to even consider a string slingshot for any kind of defense or hunting.
Now a split-stick rock thrower (similar to what the Hai-alai players use) would be a slightly different story. That's really an "extension of your arm" weapon.
But even then I might still prefer a Major League baseball or a can of Campbell's Chicken Soup thrown from my bare hands.
I think the major advantage of archery in war is the long distances a huge number of arrows could be launched toward an enemy without really sighting at all.
Now a crossbow... now that's a different story...
Terry, 230RN