How to show a fully configured crystal reprot in C# without using a dataset?

I'v designed a crystal reprot using crystal report 11.0.0.895.

I configured the connection to a database and everything is working just fine from inside the crystal report application.

Now I want to show the reprot when a button is clicked in a windows form C# application. I use this code:

        DataTable dt = supervisorBLC.M_rpt_task2();
        DataSet ds = new DataSet();
        if (dt.Rows.Count > 0)
        {
            ds.Tables.Add(dt);
        }

        ReportDocument reportDocument = new ReportDocument();
        reportDocument.Load(@"C:\Users\msabry\Desktop\Report1.rpt");
        crystalReportViewer1.ReportSource = reportDocument;
        reportDocument.SetDatabaseLogon("sa", "P@ssw0rd", "(local)", "FirstTask");
        reportDocument.SetDataSource(ds);

        crystalReportViewer1.ReportSource = reportDocument;
        crystalReportViewer1.Refresh();
        crystalReportViewer1.Dock = DockStyle.Fill;
        this.Controls.Add(crystalReportViewer1);

It works just fine.

My question is why must I use a dataset and populate it with data from the database while the report itself gets everything it needs from the database directily? Can't I just give the ReportDocument object the path to the already created report and give this document to the viewer?