I could play my entire life and never achieve the level of play Lee Sedol has. AlphaGo surpassed that level in a matter of months.
As a matter of fact, many professionals that play the game for a living as their main occupation, since they're kids, will never achieve the level that Lee Sedol has.
Also from here, they can add more infrastructure and feed the bot with more training data and let it train for a longer time, and it will be distancing it more and more from human level play.
Then, this task specifically is not just any random task... it's one of the most complex games, one the oldest games, and is also professionally played and studied.
Then, AGI is not a requirement for disrupting our world. You can have ANI for one specific task that is performed by millions of humans and you have disrupted the world enough to make it a problem.