As a word of clarification.
The article you linked is actually also the one on which our currently preferred economic model is based (in a modified form to allow good quality to be taken into account).
However, keeping a market on each tile is impossible due to RAM constraints. I mentioned cities/settlements in my post above for a reason. We can have about 20k entities storing pops per million tiles. These cities then have territories from which they can extract resources (through farming, mining, fishing, woodcutting, foraging, hunting and other means). Rural population is stored on a separate list on those entities.
I'm under impression some people see tiles as our equivalent of provinces from Paradox' games. They're not. Settlements are. Tiles act as dynamic pixels to define environment for settlements so that things like available resources and farming rates can be determined.