The important thing about their work is that it is deliberately marching down the path of more and more complex world simulations.
We experience the world at one second per second. To learn to walk we must first fall, and we fall at 32 feet/second^2. There's a hard limit on how fast we can make mistakes (like tripping) and so there is a hard limit on how fast we can learn.
Computers can experience a simulated world at many hours per second. When they're learning to walk in a simulated world they can fail, and learn, thousands of times before we've finished our first step.
This ratio of simulated experience to real world time is also going up. Eventually the minimum amount of time it takes to grow a toddler like AI in simulation will be just under the time an AI researcher is willing to wait for results. When that happens we'll see a real improvement in the quality of AIs.