Spreadsheet templates are used for many reasons and each template vary according to the purpose it is used for. Spreadsheets are designed with different calculations depending on various needs.
For pure data analysis, the spreadsheet is, indeed, king. To a point...Despite all of these extremely powerful features, the spreadsheet has limitations, which tend to manifest when you least expect it. Often, Murphy's Law applies and the spreadsheet falls over when you are right in the middle of a major undertaking, like month-end or meeting a tight deadline.
You may want to create a workbook with multiple sheets for various aspects of your budget. You can have one sheet that keeps track of savings and investments and another sheet that lists your monthly bills.
Not dynamic : Data ranges become redundant when new records are added, resulting in established formulae needing to be altered. Overlooking these errors can be embarrassing and downright expensive, especially if important decisions are being made based on the data.