In cities all over the world, people are reproducing less and less. Many governments have programs to encourage people to have families because it is important for the economy and sustainability of the country.

The number of children born to a given family has fluctuated over time. It's not absurd to say that the shape of our society influences family planning.

In fact, there are capitalist countries (coughJapan) where encouraging baby-making, in the face of a demographic crisis that threatens to catastrophically disrupt economic stability, is state policy.

Capitalism usually means a small owning class and a large working class, which is the hierarchy. It doesn't actually require a pyramid scheme system of recruitment, you could just have an enforcer class that beats the workers into hopeless submission and consumption. The way it works now though is that workers at every level are led to believe they can rise up the pyramid. This is a good complement to the raw violence which is still there: this belief reduces enforcement costs, encourages consumption, and allows for some necessary meritocratic elevation to the educated technical/bureaucratic class.

The alternatives that you listed seem likely to eventually lead consumers to stop consuming a product. Population growth, on the other hand, does not.

Unless, of course, we reach the inevitable point where resources become so scarce that no one can consume anymore. But that future is still distant enough to be systematically ignored. Hell, even climate change is still being barely addressed.