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

Why is Security boundary important in Laravel applications, and what problem does it solve for developers? The key reason to understand security boundary is that Laravel applications are usually composed of several layers that must work together predictably. Mass assignment protection reduces the risk of a request setting attributes such as role, status or ownership fields accidentally. 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: Mass assignment controls which attributes may be assigned through methods such as create and fill, helping prevent unintended fields from being populated from request data. The specific focus here is security boundary: Mass assignment protection reduces the risk of a request setting attributes such as role, status or ownership fields accidentally. 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.