varietals...

[Doug Holdsworth]

I do realize that a varietal wine must be composed of at least 75% of the said grape in order to be a true varietal wine. One thing I am confused on, however, is why this isn't the case for all grape varieties. What I mean is, for instance, Moullin A'Vent by Jadot is made entirely of gamay. Why isn't there such thing as a "gamay" varietal? If there is I've never heard of it. Any thoughts?