There are some key points there. A crucial one is "why did capitalism work"? Some preconditions were required. One seems to be growth. Piketty makes that point at length of course, as have others. Capitalism did not create growth; technology did. Before the Industrial Revolution, GDP in Europe increased by a few percent per century.
Weinstein makes a less common point: the capitalist working and middle class depended on "the ability to train briefly in one's youth so as to acquire a reliable skill that can be repeated consistently with small variance throughout a lifetime, leading to what we've typically called a career or profession". That's broken down. Few people now have the same job for a lifetime. Or even a few years, now. For most people, the return on investment for higher education has gone negative. And, as he points out, any repetitive job is likely to be automated.
Weinstein makes the usual mistake of jumping from trying to identify the problem to proposing solutions. One of Piketty's strengths is that he admits he doesn't have a solution. Proposing solutions too soon turns the problem political too soon.
Weinstein has an incredible resume.[1]
[1] https://www.ineteconomics.org/research/experts/eweinstein