Because climate change is the only reason to do something like that - we need to solve the short term issue of pollution, because in the long run (e.g. a few centuries) overpopulation is not a problem as we're going to get a population stabilization and decrease just with current trends without a need to sacrifice anything for it; and we are getting more resource efficient over time, GDP growth has now finally (unlike all history) decoupled from growth in energy use and mineral use, etc.

Climate change is a problem that makes us need a rapid solution right now even if its costly and painful, general depletion of resources really isn't; if it wasn't for climate change then we could just let the replacement of oil to renewables happen "naturally" as oil prices slowly increase as the supply decreases, the usual market incentives would be enough to manage the resource allocation.

Finiteness of resources is not as big of an issue as it looked in 1970s (when the original Limits to Growth study was made) - with a stable or shrinking population (current situation in developed world, soon-to-arrive globally) each person's share of physical resources is the same all the while as each person's need for physical resources (except energy) is not growing now (unlike 1970s), with advances in tech meeting the same needs now requires less resources so we can continue to grow our economy within the limits of the same finite resources.