They're marketed as "dual purpose" but they're supposed to lay upwards of 250 eggs a year, and combined with the fact that they're sexlinks, I don't think broodiness was something the companies wanted.
I did see that the local TSC was selling sexlinked Asian black chicks with a picture of the...
I've never had Asians myself, but they're highly developed production birds, and breeders strongly discourage broodiness in their high-production lines.
It's difficult to completely overcome such an ingrained instinct, so the occasional broody sex-link does pop up, but you're unlikely to get...