AlphaGo had a trivial simulator for the Go game, so it could play millions of self play games. Reality is not so easy. We need a simulator for reality, not for go, in order to reach human level. The author emphasizes the need for a nurturing, challenging environment, and difficult problems that are within its capabilities to solve, for the agent to become more intelligent. In other words, the AI needs good data to train on, and that is the bottleneck, not the AI itself. That's why there can be no AGI - there is no universal data.