Why is Relationship inclusion important in Laravel applications, and what problem does it solve for developers?

Why is Relationship inclusion important in Laravel applications, and what problem does it solve for developers? The key reason to understand relationship inclusion is that Laravel applications are usually composed of several layers that must work together predictably. Resources can include related data when those relationships are intentionally available. Ignoring that boundary can lead to duplicated logic, poor security, unnecessary database work, or code that is difficult to test. Why it matters in practice: API Resources transform models and relationships into controlled JSON representations so APIs can expose a stable response structure. The specific focus here is relationship inclusion: Resources can include related data when those relationships are intentionally available. This question is designed to test not only terminology, but also how the concept fits into Laravel's request, application, database, security, or deployment workflow.