Dates require their own set of specialized functions. They work differently than regular numbers requiring the user to take more care when using them in formulas.
Dates can be sorted into a list in chronological order. They can be subtracted to find age or duration. Dates can also be used as multipliers in other calculations such as determining interest on a bond.
Using dates and times in Google Sheets works differently than using numbers. Spreadsheets need their hand held a bit tighter to figure out what is a date or time, as opposed to what is just a string of other characters.