Earlier quoted context omitted.
That reductionist analysis treats people as individualised economic drones. What do you mean by "productive" - earning a salary? Contributing to civic society? People don't just do nothing if they have means. Inheritance tax damages filial peity and encourages the disintegration of society.
A hobo is less damaging than an unproductive trust fund kid. Many people contribute nothing which directly disintegrates society no encouragement required. If a moderately larger inheritance seems to impact filial piety then it didn’t exist in the first place.
In reality, inherited wealth leads to the security which can result in great feats in music, the arts, new business, and the growth of civil society.
And encouraging generations to rely on one another directly, rather than via a welfare state, ensures that people take care of each other properly.
The alternative is the sort of degenerate individualism which has so severely weakened western society.