You are close, but not quite on point. The issue you discussed isn't really an issue that utilities face under normal circumstances, the law of large numbers t

You are close, but not quite on point. The issue you discussed isn't really an issue that utilities face under normal circumstances, the law of large numbers tends to take care of that. Utilities typically use these systems to control the load during abnormal usage periods such as during a period of particularly hot outdoor temperatures. By throttling their customers AC usage, they can reduce demand and avoid risking blackouts/grid failures or having to resort to using 'peaker plants' which tend to be older and more polluting (and due to latency requirements, must be kept up and running for the entire peak period, even if they are never needed).