I'm not a technically strong developer, but is this true now or after a couple of years? What kind of systems are we talking about here?
This is my observation based on working with AI. AI seems to mature just like people mature. It has progressed from an intern into a staff or senior level engineer. I still see it making bad decisions on security (mostly errors of omission) and the quality is still greatly dependent on the the instructions. I do think this continues to get more advanced over time. What I am looking forward to understanding is what does a code base look like that's been 99% developed by agents over a long period of time. These early agents may be technical debt engines at scale.