It is basically what "the AoS twist" is, break the cliche, we could say. Take something that became too associated with something and try to modify it. Dwarves are renown for theit tradition, then would they become without them? We get KO. Elves hate dwarves and vice versa, then what could happen if they try to build functional communities with humans - we get CoS. What if heroes after death do not get their feats and celebrations but a chance for revenge - the result is SCE. Same here: "Elves" are associated with something light and agile, but maybe they would contrast nicely with hammers. And thus we get Stoneguards. Also FB being not exactly thinkative about its sources of inspiration - we have got ourselves in a situation where two very different "patterns" for fantasy elves: aes sídhe from irish folklore and hermanic-scandinavian álfar were heavily mixed, despite being drastically diferent. Because of that elves in world-that-was we have are those "classical" delicate loves of long swords. In Age of Sigmar, where GW tie almost every faction to some sort of follore origin, be that some specific folk tale, general collection of various folk tropes combined between each other by folklorists through similiar themes, or basing on common leitmotives of mythos. And thus we get Idoneth who are very close to the themes of isolation and retreat found in the stories of sidhe, and Lumineth who are obviously way closer to alfar, the latter never being associated with grace and elegance directly.