That pain also comes if you're already deeply invested in cloud products. Nothing scales without effort. And pain points always arise where you don't expect them. But the simpler the setup, the simpler it's often to scale out the parts that need scaling. In this example maybe a dedicated server or a separate database server at some point. But there can be many customers before that's necessary.

Preemptive scaling never really works and most projects never scale enough to warrant more than one server (unless you write very inefficient code).