Ummm, my comment was on-topic, since if Piketty's arguments for wealth-confiscation depend upon his research; if his research is wrong, then his conclusions are likewise unsupported.

And yes, when writing software we should use the appropriate tools for the task. If we're about to advocate the confiscation under force of a significant proportion of the world's wealth, then maybe--just maybe--we should use more complex, more expensive but more complex software development methods than 'bing into Excel and fiddle with the formulæ until they feel right.'