Are you thinking specifically of the US or you thinking of all the countries that were part of the data they reviewed? Also, how does leaving the wealth in the hands of citizens prevent it from being taxed in the future if needs be?
Not taxing the citizens now gives you more room to tax them in the future. Or looking at it another way, cutting those currently implemented taxes can act as a stimulus for the economy, although one with poor measurability compared to other types of stimulus.