Yes that is entirely true, but the world of Go is very small and unambiguous in terms of goals, rules and so on. A little less than chess, but it's still a game with a well structured world and simple rules. AlphaGo understands as little about Go as Stockfish does about Chess or your TI-83 understands about maths. That they're good at it has almost nothing to do with (generalised) intelligence, and it's no coincidence that the performance of RL say, in games is insanely better than it is when applied to real-world, open-ended problems.

Deep Mind made a 'superhuman' Breakout bot, but if you messed with the panel at the bottom it sucked. It hadn't learned what the panel is or what the game is about, it had just learned to rearrange pixels. You can get away with this in one version of Breakout, but in the real world it's brittle and useless