The article seems to be making the argument that - these "megasites" were bigger and more urban than your typical Neolithic village, and certainly than a typic

The article seems to be making the argument that - these "megasites" were bigger and more urban than your typical Neolithic village, and certainly than a typical group of nomads or hunter-gatherers. - normally, increased urbanisation like that would lead to increased levels of inequality, for the reasons you mention (you can acquire more material wealth through specialisation, and it's easier to accumulate it when you don't have to carry it with you) - but actually, from their analysis of floor plan sizes, there wasn't as much inequality as we might expect. It seems a little tenuous to me. I'd like to see their conclusions when you add on the error bars for "just how strongly family wealth correlates to house size", "how accurate is our distribution of house sizes given we only recovered X% of them" and all the other assumptions being made along the way.