I have no problem with people being productive, but I'm not okay with productive people imposing their productivity on other less productive people, in the form of social filtering, unemployment, elitism, etc.

The last 100 years have seen amazing increase of productivity thanks to technology, not thanks to methods of resource management.

Climate will exacerbate inequalities, and I think productivity doesn't really matter anymore, since a lot of jobs seem wasteful of resources, yet they are still valued for no good reason. Many people who are high earners often have trouble understanding the meaning of what they do, while other in poverty would appreciate being given a fair access to basic resources, without feeling guilty of not being a productive member of society.

It's funny because Milton Friedman advocated for a basic income, or a negative income tax, so it's quite compatible with capitalist values. The problem is not really capitalism per se, it's more how we value the necessity of effort and mutual help. Rejecting the weak doesn't lead to healthy values.

"From each according to his abilities, to each according to his needs" is a quote from Marx, but also used by Kennedy.