It’s doesn’t, though. Per capita consumption varies. It’s more that a minority of our population vastly over-consumes. That problem would exist on another planet too.
That's a popular argument that falls apart when you look at the aggregate level of material wealth on this planet. Using GDP per capita as a passable proxy: current world GDP per capita is around $12k afaik, which is about where Mongolia and Indonesia are. Considering high level of inequality there (when you go there as a tourist, you're exposed to the wealthiest part of the society, and we're talking about the average), do you think people would be happy to freeze their consumption on that level? Or even lower, because most people talking about "over-consumption" also think that the current level of consumption is unsustainable?
To make things worse, there are also embedded emissions. You can see it with China, coming out of poverty requires infrastructure expenditure, which means "wealth averaged out" would be even worse than the average would suggest, as you can't average sewers and highways, you have to build them anew.
There is just not enough wealth on this planet as it currently is. When you're saying "they'll be happy far below the most conspicuous of over-consumption", it actually means "worse than an average citizen of Mongolia, forever", which doesn't sound as enticing, does it
That would assume GDP is a measure of resources and production capacity as opposed to just vaguely correlated. It would also assume there is no way to reduce unnecessary production costs, like profits.
It’s entirely possible to start from today’s resources and build production far more efficiently if we produce rationally for use.
Look at the scale of the numbers involved, profits are around 15% across developed economies [1], which is not nearly enough to offset the difference between average Mongolian and what you'd consider a decent QoL.
I don't see any evidence for that claim. What's more, planned economies don't seem to be particularly efficient at reducing waste or improving QoL, examples are plenty, from lake Karachay to unavailability of basic feminine hygiene products in USSR up until its breakup.
