Your quote hinted at limitless growth, which is impossible on Earth.
Hence the need for the qualifier "without resource limitations". This can temporarily be achieved in many ways, from increasing energy efficiency (creating more with less energy), to colonizing other worlds.
Actually, other resources are potentially less limiting compared to energy. With improved recycleability in products we could produce goods for far longer (if not indefinetely). Materials development and waste management has a long way to go, but, with these issues developed properly, we can continue to keep making things for years to come, until we reach a limit on energy use.
History tells us that energy efficiency measures actually increase energy use in the long term. And there is a limit to how efficient a device can become. Some devices are already pretty much at their limit.
Energy efficiency improves our lifestyle, and any temporary saving usually results in a net increase in energy useage overall.
Problem: steady state economy (whichever version you prefer) in no way solves this issue. Our current existence, with current technology, is not sustainable indefinitely. Putting a lid on growth reduces the strain on resources and makes the timer go longer, but that's it. It doesn't solve anything, just kicks the can down the road. Worse still, forcing a steady state economy could potentially reduce the pressure to find other sources. Off planet, if necessary.
A steady state economy is needed, as it is the most sustainable solution. Resources such as mineral extraction is potentially a temporary problem, as we recycle more and more (assumes renewables will be used in the future as well).
A forced steady state economy could be a disaster. It is one of the great challenges for future generations for how to acheive this without conflict. If someone comes up with the solution, it will on a par with bringing us affordable fusion energy.
Off planet solutions look to be small scale, and largely robotic in the future. And lets not forget the amount of energy every kg of gear it takes to get in orbit (LEO or otherwise). So before you start saying space is part of the solution, we need to address the energy part of that equation. Manned missions bring their own difficulties of course.
I would love space to be more of the solution, being a bit of a scifi fan, but the energy issue will not go away, and space is a difficult place to exploit.
Which is why I said we need to define what "need" amounts to. A growing economy is currently one such debatable need for the vast majority of people directly affected by it, which you dismiss out of hand and claim a steady state economy is needed. I think I made my point as to why such definition is anything but irrelevant?
I would argue that defining "need" is pointless at this point, as a population's need changes with every generation.
Certainly a first world living standard as of today is what most people in the world would like, but it wouldn't suprise to see wars breaking out if a country has to acheive that living standard. That is still a need by many definitions.
Getting 9 or 10 billion people (or however many we level off at), living a first world living standard is the challenge. Once we get food sorted (and this is acheiveable), it is energy that is the problem, and the increase in energy consumption. Efficiency will not solve this, I hope we both agree.
