It does sound like the brake hood position centerline is still where the width sizing measurement is taken, and the reason they are recommending wider than the old standards is so you have more hand positions available on the horizontal flat part of the bar. On my 40cm Cinelli, there’s room for about one hand position on the horizontal. Next position is on the curve with my fingers on the outside, then the last position is on the brake hoods themselves. Nothing on the drops.

With my height, seems like 46 would be right for me with respect to the last couple of posts.