Function as a Service (FaaS) is a growing trend in cloud computing. It's an opinionated approach to helping users write cloud applications that scale. A central tenant of cloud functions (and what really makes them effective) is their stateless nature. They handle requests then disappear. Nothing is ever permanently "on" which is why they're so cost effective for the cloud provider to host and manage.
Of course, there are times when it does make sense to handle state. But this does not mean you should clutter your stateless function code with state-related functionality. This is better left to an orchestration engine or similar event-driven strategy that is external to your cloud function. This gives you a proper separation of concerns between what is stateless and what is not (which is what you're really after with serverless architectures).