That kind of makes sense, however the point was more that AI progress isn't gradual and continuous. It's (sometimes) rapid and has discontinuities. Alphago was

That kind of makes sense, however the point was more that AI progress isn't gradual and continuous. It's (sometimes) rapid and has discontinuities. Alphago was an entirely new method, using deep convolutional neural networks as a move generator. Therefore there wasn't any guarantee that it had to be just slightly better than previous Go playing algorithms, it could have easily been far above humans. Likewise this is also the first time Go AI has been given Google scale resources. Both in terms of a team of the best researchers working full time on it, and their computing power. Whereas previous Go projects were all hobbyist things. And Google didn't wait 10 years to challenge Sedol. The match was arranged only a few months at most after they started developing it.