Reefing and weather helm

I'm not convinced that reefing the jib will always decrease weather helm as stated in the text. The jib's COE does move forward, but it also gets smaller and is less able to counter the COE of main. Imagine rolling up the jib all the way. There would be no force at all to counter the main. At some point when rolling up the jib, the weather helm would increase. I suppose partially furling a large genoa could decrease weather helm, because the part of the sail that disappears was pretty far aft to begin with.