Because Excel is a spreadsheet, for calculating with numbers. Then there's additional code for dealing with all the inconvenient ways people format things, or

Because Excel is a spreadsheet, for calculating with numbers. Then there's additional code for dealing with all the inconvenient ways people format things, or want to add text labels, or do things closer to numerical/financial analysis, or all the other extras wrapped around the core "put numbers in boxes and do math". That misunderstanding is at the core of Excel misuse.