Originally Posted by gomestar
and to jump on Serg's point, the white blending is often used to soften the wines up and make it more approachable in its youth. If a growing season is really off, this will help balance out the wines. The same thing used to be done in Chianti for years, but I'm not sure if there were other reasons (I'll check my notebook, I remember discussing this with a professor).
Why viognier and not chard, I couldn't say...