If you want the bot to avoid winning by micro, you add delays, cooldowns on interactions, imperfection on clicking, misclicks, etc. on the level of a human pro.
In any case, simplifying the game is usually done to make training far cheaper.
But the human competitors also require large amounts of training in order to competently play Dota 2, and their training is not simplified that training in a similar way. I realize that "fairness" is not really the point of having humans play against bots, but doesn't it damage the usefulness of the comparison from having them perform a human activity?
In any case, simplifying the game is usually done to make training far cheaper.