When is it a Good Idea to Decouple Drupal and Why?

"In a conventional web project, Drupal is used to manage content and to present it. In this sense, it is monolithic because your entire project sort of “lives” inside Drupal.

The concept of decoupling implies managing different content layers separately, with an agnostic presentation layer. To be precise, it is the communication between backend and the frontend via API.

It will help you better under stand situation where decoupling will make better sense."