My guess is that 8th gen was picked since that's when quad core became standard across the product line, but that leaves out the earlier HQ series (such as the

My guess is that 8th gen was picked since that's when quad core became standard across the product line, but that leaves out the earlier HQ series (such as the i5-7300HQ on my ThinkPad T470p) that are quad core. And of course the Celerons aren't either, so it doesn't make any sense.