It makes no good sense to evaluate models we don't have access to. For all we know K3 was competitive back then too. Or maybe there's a K4 in the works that blows everything out of the water. Who knows and who cares. There's no way for us to compare
Mythos was withheld because of the threat to security and/or marketing stunt (depending on your leaning), I don't see what benefit there could be for not releasing K3 immediately.