Are foreign keys really necessary in a database design?

Question

As far as I know, foreign keys (FK) are used to aid the programmer to manipulate data in the correct way. Suppose a programmer is actually doing this in the right manner alr

Answer 1

Yes.

1. They keep you honest
2. They keep new developers honest
3. You can do ON DELETE CASCADE
4. They help you to generate nice diagrams that self explain the links between tables