There’s also something to be said for more complex games, in some ways, making things easier. Go and chess have been studied for centuries, and are very mechanically simple, and strategically deep.
But a game like DOTA has orders of magnitude more complexity. Now this certainly makes creating an AI to play, at a basic level, harder. But the distance from able to move and use mechanics, to being able to play level and beat human players? Probably much smaller. People haven’t optimized and analyzed to the same degree, and with more things to track/ do it is easier to have a human player make a sub optimal move.
This is not to shortchange the AI design, or top tier human play, but merely me hypothesizing that humans have not reached the same tier of ‘perfection’ in terms of the absolute theoretical range of play. So if humans have achieved 98% of whatever theoretical perfect play is in chess, they’ve probably only gotten 80-85% of such in DOTA.
Add in rebalancing, new mechanics, tweaks, character numbers, and I can easily envision the task requiring less optimization. Especially if limited in scope to a single character play.