Spokes have more air resistance than the disc; cyclists learned this long ago. They also learned that in crosswinds, the fool with disc wheels is in trouble. Back in the '80's, they ran time trials in the Red Zinger races with disc wheels on the front. In Colorado. Where the wind never blows. yeah, right. They no longer do such foolish things. But you do see roadies with 40-60mm deep rims.