Efficient Sudoku solvers require knowing more than a little about search algorithms, but are easy if you know more than a little about search algorithms. Go has a ridiculously large search space, it would take a lot of insight into Go to hand-roll a heuristic for it. AlphaGo learns the heuristic so they didn't have to be clever, they just had to throw a lot of big iron at training it, after which you have a program that plays Go well and have demonstrated that if you have the big iron to throw around, just throwing big iron at a problem is often an effective way to solve it, but haven't really learned anything about Go or Go players. I'm becoming more sympathetic to Chomsky's complaints about statistical results in computational linguistics by the day.