The author champions Adam Smith, but can not possibly have read him. He did in fact speak at length about the dangers of inequality. He specifically said that poverty was not an absolute phenomenon. It is not about how many calories you get per day and the size of your dwelling. He understood hundreds of years ago that poverty is a relative phenomenon.
The author also mentioned Picketty but elegantly ignored his reasoning for why inequality is a big problem. One of the things Picketty pointed out is that with rising inequality, inherited wealth starts dominating the economy. This means the ability to get rich fast will most efficiently be accomplished with strategic marriages rather than starting your own businesses. This is what the world of Jane Austin was about. Everything came down to strategic marriage. That was the obsession of the day. A society of high inequality over a long time can not be a society of "the self made man".
That ought to be recognized as a problem.