You know what they say about first impressions. If you can greet, inform, or engage your audience in three steps, they may decide to 'go through the pain' of giving your app a try.
It's best not to leave things up to faith to make an impact. Grooming and preparing yourself before a speech are critical to deliver a memorable message; one that galvanizes audiences to take action and/or walks them by the hand as they navigate and become familiar with your application.
In paraphrasing the Material Design guide, we can deduce that onboarding is far more than just an introduction to your product or service. It extends from the initial stages in the buyer's journey the moment someone learns about your app, downloads and opens it, to the point where the user converts and becomes a repeat customer.