So is e-sports, for much of the same reasons; audience event, even playing field, auditors/judges etc.
For the video game market in general, AI will be used by players largely where there are financial incentives (MMO market, CS:GO Skins, etc.), but usage of an AI will most often be socially viewed just like usage of any other performance improvement/script/hack: As a crutch.
games like CS its less useful because it will be blatantly aimbotting. as it gets better it will be more and more obvious. you might be able to train it to mimick human mistakes, but i think ultimately it will be easily spotted by other players. for games without the hand-eye-coordination like turn-based games or games with 'global cooldowns' , mmorpgs etc., it will be much harder to identify.
i think normal subtle cheats like ESP when 'done right' are much more killing esports than this would.
You can't bring your motorcycle to the 100 meters, nor can you even wear certain sort of fabrics in swimming competitions.
It's not cricket if you throw rather than bowl the ball, you can't run with the ball in basket ball.
So what you are talking about is enforcement - cheating in online games is nothing new.
On the wider point - I do think good AI might open up a whole class of strategy games where some of the grind is taken out of the game, and the player ends up being much more of a strategic general type.
What happens when a team of humans are playing against a team of AI, which play in the same conditions, with network lag etc. from a client computer perspective...
And consistently beat the human counterparts for being faster at response time, never make mistakes and not ever getting tired?
Eventually it could kill all MMOs, fill them up with AI players, "farm" with AI that never sleeps, ruin counter strike type games online, etc. Another arms race?