The number of edge cases in a software is not fixed at all. One of the largest markers of competence in software development is being able to keep them at minimum, and LLMs tend to make that number higher than humanely possible.
The people pushing AI _over_ humans never thought they were. They just don't care about 'good' or 'bad', only 'time-to-market'. A bad app making money is better than a good one that isn't deployed yet. And who cares about anything past the end of the quarter? That's the next guy's problem.