I think their hypothesis would be much better supported by typical social science approaches, such as citation and quotation of primary sources and comparative study.
For example, how does the Sicilian Mafia compare with the Camorra (Naples) and 'Ndrangheta (Calabria)? Did these organizations undergo a similar expansion during the same time period? Were their origins and expansions rooted in similar phenomena?
[1] https://aeon.co/essays/how-economists-rode-maths-to-become-o...