[anononaut]

Before that, weak amateurs were just replicating human joseki. That's nothing new. They definitely give a player a good start, but knowing which to use and when, and of course how to follow up until the game is over is no simple task. It also happens to be the case that AlphaGo, KataGo etc. prefer simplifying the board state. Remove complexity and win only by a thin margin, because that's all that's needed. Memorizing AI preferences is much easier than some of these highly complicated joseki.