Final classes bring much more value than `extends` it lacks. It teaches composition over inheritance, makes upgrades easier, and [even mocking](/blog/2019/03/28/how-to-mock-final-classes-in-phpunit) is fine. If you're lazy like me, you can [automate the `final` keyword addition](/blog/finalize-classes-automated-and-safe) to your code - quickly, safely, and check it the CI!
