I tend to agee with this view. As the wing tries to flex spanwise from g-loading (the most severe stress it will experience), the upper and lower spars will try to "slide" relative to each other, and shear web with grain parallel to the spar would tend to shear along the grain under this stress, whereas the shear web's grain running perpendicular to this "sliding" movement would resist the motion, permitting less flex.

Unless it's a fairly small (5 pounds or less) model, I use lite ply for my shear webs, with the 2 outer plies perpendicular to the spars. The more snug the fit between the ribs, the more the stress loads are carried by the material and not the adhesive.