If we had no calorie restriction why would we have evolved.

That's true, we evolved to adapt to calorie scarcity but our environment has changed: calories are now abundant but our system is still optimized for scarcity despite that constraint no longer existing. I'm sure in a few thousand years that'll go away (possibly faster, as we get better at manipulating our own biology) but the status quo is that we're poorly adapted to our environments, energy-wise.

In an energy-rich environment, evolution should select for faster and faster reproductive rates.

Perhaps so, but humans are reproducing later and having fewer offspring, so there are more variables than just energy.

Environmental stresses are well-known to cause reproduction rates to plummet. That can be because of a lack of available food, but it can really be any sort of stress.

Excellent point.

But note that calories scarcity is a simplistic model.

What I'm trying to show with what I was saying, is that there are stocks of scarce molecules imposing performance limits too.

underrated perspective

Something else would end up scarcer

This feels like it may fall into the realm of "I think if we just throw money at it we could solve it" problems that you can't actually solve by throwing money at.

Metaphorical money thrown at evolution several million years ago, namely calories. You were built on a budget, just because it's still better than anything we could make doesn't mean it's the best evolution can do under lesser constraints

If we had evolved without caloric restriction in an "easy" energy-rich environment where there's less competition for scarce energy and thus complexity and intelligence aren't absolutely mandatory to acquire it, evolution should select for faster reproductive rates by simply sacrificing complexity, not building some kind of more complicated support structure.

Well yeah, obviously. It's just a dream after all