That "we" is undefined and thus meaningless. But people who have to write and run applications in the real world know that the I/O from any lookup is orders of magnitude more overhead than all but the most extreme calculations.

Apparently CELKO doesn't understand that computers perform billions of mathematical calculations per second.

Where possible, use calculations when appropriate rather than wasting extremely expensive I/O to do things that can be done with a nanosecond or microsecond calculation.