>Now when we say that our economy grows exponentially, it means that the amount of matter traveling through this pipeline is growing exponentially too!
The relationship between economic growth and environmental damage is more complicated than this. Something like transitioning from fossil fuels to cheap renewables is both a case of economic growth, and a reduction waste matter. Similar principles might apply to everyone having an iPod instead of buying new CDs, miniaturization in computing, productive uses of what used to be considered waste, building mass transit infrastructure over cars, etc.
If you want to slow damage to the natural environment, I'm all for it, but if you aim to do that by slowing economic growth, rather than accepting slowed economic growth as a potential side-effect, you're throwing the baby out with the bathwater. Economic growth often means more people can have better lives using fewer resources.