Creating a 3-statement model enhances the accuracy of the model. If the balance sheet balances, that is very useful proof that the model is working.
Furthermore, lenders and investors may wish to see the value of the assets and liabilities, as well as changes in the balance sheet over time. Lenders will often use the assets as collateral in case the company defaults on its interest payments.
The company may also be doing add-on acquisitions, and it’s useful to see how the value of these acquisitions is being allocated between PP&E and goodwill since the assets can provide additional collateral for lenders.