> With your own code you reasoned about it which contributed to its stability.

Okay but to what extent? People say this but there's no way to measure it really. Did you live through the 90s? People reasoned through all that code and it was very often quite unstable. I'm sure everyone involved with Windows ME reasoned about it quite a lot, probably elements of it locally were very sound, yet in totality it was an unstable mess.

What fixed that situation wasn't that engineers today are reasoning better than engineers in the 90s, but IMO better tooling. Which brings me back to: your codebase is only as good as what it can prove. If there's any question, I just show you the proof rather than appealing to my reasoning being sound.

> With unreviewed AI gen nobody ever understood or reasoned about the code, including the AI.

And? You haven't established reasoning about it is actually necessary and it certainly isn't sufficient.