Why LSP Matters for WordPress Developers
When your class hierarchy respects LSP, you can pass any subclass anywhere the parent is expected — and everything just works. No surprises, no crashes, no instanceof spaghetti.
Predictable Behavior
Subtypes behave consistently — no hidden surprises when swapping implementations
Easier Testing
Test with the parent contract — all subtypes pass the same tests automatically
True Polymorphism
Write code once against an interface — swap implementations freely without touching callers