Not at all. The benefits of using the API.AI in creating a conversation action include understanding natural language and expanding grammar, filling out a form, matching goals, etc.
Nevertheless, the Actions platform by Google platform includes the CLI, client library and Web-simulator, which can be used for the development of Action, totally independent of the API.AI . To do this, you need to create your own package of actions that describes your Actions and expected user grammars, as well as an endpoint that will serve helpers' requests and respond to user requests. You can use the CLI to deploy your action package directly to Google, and you can host your endpoint on any hosting service you want. Google recommends using the Google engine in the Google cloud platform.