Take for example the following: > Another correction concerns the tax reforms passed under Ronald Reagan in 1986. Apparent changes in top incomes around this reform account for about two-fifths of the total increase between 1962 and 2015 in the pre-tax incomes of the top 1% in Messrs Piketty and Saez’s estimates. Messrs Auten and Splinter say this is an illusion. Reagan’s tax reform created strong incentives for firms to operate as “pass-through” entities, where owners register profits as income on their tax returns, rather than sheltering this income inside corporations. Since these incentives did not exist before then, top-income shares before 1987 are liable to be understated.
In essence this just says that it's possible the rich used to be overwhelmingly rich even before the Reagan era reforms, hence inequality might not have increased that much over the past decades. This is hardly comforting for the average person.
Or take a look at the conclusive paragraph: > While that long and bloody academic battle takes place it would be wise for policymakers to proceed cautiously. Proposals for much heavier taxes on high earners, or a tax on net wealth, or the far more radical plans outlined in Mr Piketty’s latest book, are responses to a problem that is only partially understood.
Doesn't it smack of "the science is not in yet" argument used by climate change deniers?