Productivity is the creation of goods and services. Goods and services are the building blocks of wealth: one who has more goods and services is more wealthy. It is impossible to create more wealth without increased productivity.

Now, to your point, the fruits of productivity could be unfairly captured by non-producers, in which case wealth is being misappropriated from those who created it to those who have the power through whatever form to capture it (i.e., taxes, feudal land ownership, etc).