People are living with it until they stumble when an innocent expression

   (a + b) >= c 

suddenly fails to work. For instance, in Excel the expression

   A1-B1-C1 >= 0

returns FALSE when A1=2.03, B1=0.03, and C1=2. Such an expression can be used for instance to filter records that fall within a certain range, and that filter would produce wrong results.