The amount of damage a newbie programmer without a tight leash can do to a code base/product is immense. Once something is out in production, that is something you have to deal with forever. That temporary fix they push is going to be still used in a decade and if you break it, now you have to explain to the customer why the thing that's been working for them for years is gone and what you plan to do to remedy the situation.

A newbie without a leash just pushing whatever an AI hands them into production. O, boy, are senior programmers going to be sad for a long, long time.