The API itself has methods to manipulate content, no problem. The issue is more about authentication and security model. Most of the APIs Drafts integrates with allow an individual user to authenticate and perform actions as themselves. For example, you log in to use the Twitter API using your personal credentials, and actions taken with the API appear on Twitter as having been done by you.
The Notion API is set up to create “integrations”. Only a single instance of the integration is authenticated in a Notion workspace, and actions performed using the API appear as being performed by the integration, not the user, additionally the resources (pages, databases, etc.) in Notion which the integration has permissions to act on are not the same as that of an individual user, and integrations must be added to a workspace in Notion just once by an administrator of the workspace - individual users cannot choose to add them and use them.
Nothing wrong with this, it’s a powerful model for many of the types of things Notion needs in integrations, but doesn’t make sense for Drafts.
That said, it is certainly completely possible to write Drafts scripts that use the API, you just have to create your own integrations and manage the API tokens, etc., yourself.