Firstly it might be easier. One site, one grid connection, one access road for heavy loads, one civil engineering operation, one security fence. One construction compound, fewer land owners and nimby neighbors. All the same reasons you might build larger factories or distribution centers. But more so. Pursuading local residents in suburbia is not a fight worth having.

Also, a project designed to export 1GW can connect to a regional or national grid. Then it can sell power far more widely. Connected to a local grid you have the same capacity issues as solar. Why bother?

That's kinda the design behind russian SVBR-150 (from mid 1990s, still waiting on money for finishing). Self-contained "cells" that can be delivered by railcar ready to use as power/heating/cogeneration plant. You literally need to attach normal COTS steam turbine or heat exchanger for municipal heating, and that's it as far as pure generation is involved.

For refueling you disconnect the pipes and cables, place it on the railcar, and send it to manufacturer.

Initial design for such cell was 150MW(e) each, thus the name.