I don't think he meant Excel. You can't use decimals in excel. First you will overflow immediatly (like multiply two numbers in trillons). Then your rounding will kill small amounts (like percentages). There is no alternative to floats in excel.

The predecessor to excel (multi plan) used binary coded decimal.

But there’s nothing stopping you from doing arbitrary precision decimal in excel except back compatibility (and all the thousands of lines of code looking for a float).