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

A database schema without FK constraints is like driving without a seat belt.

One day, you'll regret it. Not spending that little extra time on the design fundamentals and data integrity is a sure fire way of assuring headaches later.

Would you accept code in your application that was that sloppy? That directly accessed the member objects and modified the data structures directly.

Why do you think this has been made hard and even unacceptable within modern languages?