High-level policy should not depend on low-level details. Both should depend on abstractions. DIP is the mechanism that makes Clean Architecture possible — and the most architecturally consequential of all SOLID principles.
Martin revisits the three pillars of OOP — encapsulation, inheritance, and polymorphism — and argues that OO's true architectural gift is safe, convenient polymorphism that enables plugin architecture and dependency inversion.
Don't let your important business logic classes depend directly on concrete implementations (like a specific database driver, a specific email provider, etc.).