I suspect they could have done this, the technology certainly exists to read the screens and parse text from an image. They could also have tried to recognize

I suspect they could have done this, the technology certainly exists to read the screens and parse text from an image. They could also have tried to recognize when a human gives a wrong answer, like with the 20's question, and presumably the same logic used to play Jeopardy could interpret that statement and not give the same answer again. Watson took four years to develop and is the first of its kind. I suspect that something fancier never would have been finished, and too many features would have been a distraction from what IBM has actually accomplished.