This is one of the foremost reasons. You can set up a Drupal site, start adding content and managing content and instantly access the data via the APIs. If you don't want to use Drupal straight away as a headless CMS then the Drupal front-end is also very flexible. For a basic website, the Drupal front-end is more than enough. However, having the APIs available is nice as it means you can start to use them at any time in the future.
A Baked-in OmniChannel
Having the APIs:
- You can build a mobile app using data from your main site or you can build sub-domains or landing pages all powered by your main site.
- You have a single source of truth where you can add and update your data or content.
Web Services2 or APIs Available
Drupal provides web services such as JSON:API, RESTful Web Services, and HAL at a click of a button. For more on JSON:API I have written about using it here and how I am using it to build my business site here.
RSS Feed
For readers that want to subscribe to your site using RSS, an RSS feed is set up and ready to use.
2Web Services
A Web service is a method of communication that allows two software systems to exchange data over the Internet.
https://en.wikipedia.org/wiki/Web_service