Hi cdpizycki,
Welcome to Community! QuickBooks Online Payroll is aligned with government guidelines. For this reason, all required fields must be entered on the employee profile, before you can proceed with running payroll. This information is used for reporting income for tax and social benefit purposes.
I can appreciate that you may want to add an employee without entering their DOB and/or SIN number, however this is in place to stay aligned with Government regulations. You can review additional information from the Canada Revenue Agency, regarding when you must provide it, and when you're not required to.
If you have any other questions, please feel free to reach back out. We would be happy to assist!