Should i validate parameters in constructor?

Question

I am creating a web application following the MVC pattern.

In effective Java the author mentions to validate the parameters in the constructor of the class when creating a new object.

However i am not creating some API that will be used by third parties. My classes just accept parameters from input fields of a form which are validated before beeing submited to the server.

So in this case should i create my classes the way the author mentions in Effective java or it is useless?