This passage from the article might help answer that: "DeepMind learned to play video games by randomly taking any action it could. This may be fine for video

This passage from the article might help answer that: "DeepMind learned to play video games by randomly taking any action it could. This may be fine for video games, but in the real world it could be expensive, time-consuming, and even deadly to have a robot trying to learn by trying every possible action to see what generated a “reward” and what didn’t. So Osaro also wrote algorithms that helps computers learn by mimicking humans."