I believe you are right that it is a construct. Also, I think it was designed to be different, b/c it was built to be the DO's assassin of channelers. I think the point is that it is an assassin, just like Grey Men and Blood Knives who also function very differently than other resources that the DO and the Seanchan have. I think the Gholam is extra special b/c of its role as an assassin of channelers. And if the gholam wasn't around, things would be a little easier for the light siders. A good plot line makes the heros into underdogs, otherwise any victories they have are not as rewarding to the reader.