On a "formula field", it have to be possible to specify the type of result: text, number, money, date, time or date + time.
If we concatenate 2 text fields, we want the result to be text.
If we multiply a price by the quantity, we want the result to be money.
If we add X days to a date, we want the result to be a date.
Etc.
So, in order for formulas to work correctly in a wide variety of situations, this is very important.
Please see on the attached picture how the software "Filemaker Pro" deals with this kind of field. We need something similar on ClickUp.