Cannot Retrieve Output Parameters Until SqlDataReader Is Closed

While the SqlDataReader is being used, the associated SqlConnection is busy serving the SqlDataReader, and no other operations can be performed on the SqlConnection other than closing it. This is the case until the Close method of the SqlDataReader is called. For example, you cannot retrieve output parameters until after you call Close.

If the above claim is true, then why is the following method able to retrieve a value from output parameter before the reader is closed:

public int Something()
{
using (SqlConnection con = new SqlConnection(this.ConnectionString))
{
SqlCommand cmd = new SqlCommand("some_procedure", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("@ID", SqlDbType.Int).Direction = ParameterDirection.Output;
con.Open();
cmd.ExecuteReader();
return (int)cmd.Parameters["@ID"].Value;
}
}

You can reset the CommandText property and reuse the SqlCommand object. However, you must close the SqlDataReader before you can execute a new or previous command.

Why must you close sqldatareader before you execute new command?