Because it's a lot easier to rationalize not doing your job when it is (or at least seems to be) being done OK. There's a lot of rationalizing of decisions, when you've spent your life saying you're the expert helping people. Also, a lot easier for management to hand out a LOT more work since it looks like it's being done right.

It's like the lawyer using ChatGPT to file legal briefs... he'd feel bad and be obviously incompetent, if he didn't file anything at all, but didn't feel bad (or feel the need to check anything) once it "looked right".