Resource amount on a "This is Total War" playthrough.

As title says.

I'm playing as the WRE and have conquered the last settlement in the Sahara province and can begin to consider upgrading the buildings there. Looking at the gems resource building in Dimmidi I only now notice that it adds nothing but the resource itself, at a cost of both Fountain-points and Mask-points.

Since this playthrough is my attempt to get the "This is TW" achievement I can't trade, does the amount of a resource I possess impact anything other than the trade deals I can't make anyway?

In other words is there any reason to really have the gemstones building, other than allowing you to build the Jeweller buildings in gold-producing settlements?