The skill covers acc/speed somewhat, range is mostly down to your strength/the mass of the object/if there is anything keeping it from following a parabolic arc.
I can chuck goblin heads from the ground up over the fortifications and land them near the hatch in the little minitowers around dark pits/fortresses, can also chuck em straight through the fortifications, and that can be done with pretty much anybody with above average or higher strength, accuracy just means you can pick which goblin you wanna hit out of the crowd, which comes with skill, and whether or not it clunks them in the leg or gets lodged in their head.
Throwing small light objects is really fast turnwise, faster than any crossbow shot I've fired, trying to huck a platinum slab at someone... well, it's not gonna go far anyways, but they're gonna come slap you around while you're heaving it for sure.
Try coins, grab a bunch of copper off someone and go plink random animals with them, makes me want to mod in a slingshot actually.
Btw, gobs being in other civs isn't always due to capture, sometimes they join the military, kick ass during battles, demonstrate valor and such, and move up the ranks. Same happened with Cacame, remember.
Honestly after playing a few goblin adventurers now they moved way up my list compared to elves, I mean yeah, I can't figure out how to interact with gobs from a different civ outside of me saying "let's not fight, it's cool" and them saying "AAAAAAHHHHHH, oh, ok, sure, how are you? AAAAHHHHHH, really, that's fasci-" and then they run around a corner or something.
Only problem I have with gobs now is the constant lag due to all the chaos in the fortresses from various trolls and various gobs running around murdering each other, which is hilarious, really, but dammit it's hard to move around and find people to get info from/check for usable gear.