Entirely subjective, but I feel like serverless functions were never meant for hosting full fledged backends such as your consumer facing APIs. They were meant for event driven loads that would happen randomly, hence cold starts and the on demand provisioning. But FaaS providers blurred the line by introducing concepts such as dedicated, pre-warmed instances. Giving people a way to get away with running entire backends on them. In my opinion they are good for small parts of the system and not the entire system.