There's other factors to consider.
For example: in some areas there were small/medium coal-fired plants built right by the coal mines, and so have some grid infrastructure already present. You could replace the coal-fired component with an SMR and have a good portion of the rest of the infrastructure as-is (not have to spend effort / political capital on more grid pylons, which many folks oppose).
Or, for a smaller regional area, having more smaller units allows for more HA since each individual unit can be serviced independently. E.g., in Canadian Maritimes there is a big CANDU, which serves just fine when online, but when it goes offline it needs to be backstopped. Their demands need (say) 'only' 600 MW, and instead of 1x600MW, having 2x3GW allows for more HA. So if one units goes offline for maintenance/inspection the backstop that is needed is much less.
* https://en.wikipedia.org/wiki/Point_Lepreau_Nuclear_Generati...