Yes and no. First of all, it depends on the kind of application. It may be an ETL application, and in that case you don't validate in the client, because all you have is files. (And I more or less assume that this is ETL.)

But even if the data comes from user entry, the business rules may be too complicate to warrant to duplication of them in the front-end. Things like mandatory fields, foreign keys etc are simple to enforce, but you may have more complex dependencies.