The best examples of intelligent systems we have at this point are animal brains, which per cortical architecture(s) appear to operate on an entirely different principle - prediction. The cortex simply put is a prediction machine - not only can it predict, but this is essentially the only thing it does, and ability to predict is the evolutionary selection pressure that created it.
It's a bit odd that here in 2023 there is still no widespread agreement in the scientific community how best to define intelligence, but I have my own rather pithy definition that I believe is the most reductive:
"Intelligence is the ability to correctly predict (future outcomes) based on prior experience."
In other words, intelligence is the capability given to use by our cortex.
Why evolution put such a high value on prediction should be pretty obvious : you can now act based on what is going to happen rather than what you immediately perceive. Predict where the food/water is, how the predator/prey are going to behave, etc, etc. Prediction is also the basis of "thought/reasoning" which is essentially just a sequence of (correctly predicted) chained what-if scenarios.
It should now be obvious why something as dumb/simplistic as an LLM shows such a "surprising" degree of intelligence - because it is a prediction machine, and why "think step by step" is therefore such a powerful tool.
There are probably a dozen or more alternate definitions of intelligence that have been offered by various people, but I believe none are as reductive as mine - other definitions basically describe capabilities that a system/person would have if they were able to predict.
Reinforcement learning seems to be a misleadingly attractive idea because subjectively goal-based behavior makes sense to us, but it seems that again this is not reductive enough. The appearance of goal-based behavior is something that comes out of prediction. Part of understanding this is a brilliant insight from the much maligned Jeff Hawkins - prediction (quite literally and mechanistically) becomes action; this occurs because the motor cortex operates just like the rest of the cortex and is a prediction machine - it predicts our motor actions, and those predictive outputs drive our muscles causing the prediction to become true. Goal-based behavior is therefore based on the mechanism of prediction - predict the sequence of what-if actions to achieve a goal, and those actions will be taken. Our self-predictive actions start at birth by predicting (via self-observation) the actions we make at that stage and evolves as life experience causes our predictions to change.
TL;DR - DeepMind are riding the wrong horse (RL). Prediction is all you need.