I do note the lack of structural/OEW estimates in the Stanford study. Maybe they did it, and then did not bother to give numbers. What they do seem to say is that wing weight is small enough that even if it does undergo square-cube increase, it still remains a minor factor.

For example, compare B-36 with B-29. The 70 m wingspan of B-36 is bigger than any jets till An-124. Yet B-36 has a huge useful load and long range. At which wingspan would the structural weight start to seriously limit useful load and range?

What about An-225 and Hughes Hercules wing structural weight?

I guess the study did well in not mentioning the OEW. Most predictions are based on past aircraft and work best if one does not exceed that limits. Manufacturers have problem to guess the weight of their aircraft within 5% (see Boeing 787).

When comparing size one should compare capability, too. The A380 for example is much faster than the An-225, giving more design challenges for the wing and structural margin versus flutter.