Because AI can't take responsibility. Humans can.

A human can not only learn from their mistakes and blunders but also, until very recently, the social pressure and fear of judgement would push (some) humans to try their best.

Now however, it is less socially acceptable to judge a human for mistakes made with AI coding because we are in a time of experimentation. So the blame has to go towards AI coding. Of course, coding with AI can be acceptable, if the human using the AI is rational and responsible.

But I think the bigger implicit point is actually that perhaps experimentation shouldn't be done on real projects and products as nonchalantly.