Scaling. You can autoscale app servers by orders of magnitude, no sweat. Database replicas require much more logistical overhead and provide diminishing returns

Scaling. You can autoscale app servers by orders of magnitude, no sweat. Database replicas require much more logistical overhead and provide diminishing returns. The less demand your app places on a database overall, the more scalable it will be. (Of course, running a whole lot of simple queries can be more expensive in the grand scheme of things than one big query, so there's no one-size-fits-all solution to that principle.)