I normally don’t like using too many different software products that need installing, maintaining, and understanding; they often complicate things. Helm, however, is different, and for me fills a real need for Kubernetes deployments in these major ways:
First, by abstracting away the complexities of a deployment: at first, Kubernetes overwhelmed me by requiring a half-dozen yaml files to deploy a single application. Each of these files represents a resource with its own Kubernetes-specific jargon. Updating these resources can be done independently; whereas the way I think of an application is as a whole. Enter Helm, which can package all the resources necessary for an application within what Helm calls a chart.
Also, Helm allows developers to share application charts; you can use any the charts supported by Helm or create your own.