Anemic Domain Models, where entities are just data containers with logic pushed to services, violate core OOP principles. This pattern leads to scattered business logic, poor encapsulation, and brittle tests. The article contrasts this anti-pattern with Behavior-Rich Entities that bundle data with invariants and rules, ensuring objects protect their own state and validity.

The problem extends beyond theory. Anemic models create "God Objects" in services, making maintenance difficult and refactoring risky. Testing requires complex mocks for repositories and dependencies. A behavior-rich approach, like a `BankAccount` class with `Deposit` and `Withdraw` methods, keeps validation close to the data, preventing invalid states and simplifying unit tests without external dependencies.

Entity Framework Core supports private setters and protected constructors, debunking the myth that ORMs force anemic designs. The key is recognizing that DTOs, read models, and projections can be anemic, but your core domain entities should not. As the author notes, an object that doesn’t protect itself isn’t truly an object.