Exactly, and one of the big angles to this I have in mind is that instead of being individual capitalists hoarding surplus value, you have wealthy merchant families or clans who are more concerned with the circulation of trade goods than the raw creation of wealth.

I think (and this is me starting to veer dangerously outside of my territory) that this comes at least in part form the fact these places weren't necessarily rich with natural resources, rather they are rich in strategic geographic positions along Mediterranean (essentially global for the period) trade routes. It is more important to them to ensure that merchants keep coming to the city than to generate massive profit.