Right, but the bot needs to know who is in what position what the bets are, who folded, etc. Try inputting all of that information manually to the laptop next to you and you'll quickly get frustrated. Online poker is a fast game with lots of data points.
People have tried it and online poker sites know they've tried it, so they'll randomize images and other data. If you take a dive when the randomizations are triggered and outperform otherwise good luck trying to collect your winnings.