I am under the impression that it doesn't. I believe that come from a flawed piece of research about the GI levels of food that didn't take into account the levels fiber and other variables. When I am cutting weight I put no limit on my vegetable and fruit intake at all.
In a way, you are both right. GI / GL is a funny thing and almost impossible to predict... some fruits have very high GI / GL, some surprisingly low. Vegetables on the other hand are nearly always low, and often offer better nutritional benefits.
To make things easy (ie. to generalise) it's best to assume that all veg is good and should be consumed in abundance without limits, whereas fruit is really healthy (packed with vitamins etc), but probably best consumed in moderation. I personally find that fruit doesn't seen to fill me up as much as veg.