I have been doing this for 6 months or so now, and I am not sure that even if you have a lot more experience than me that it would make your assessment more accurate, since that just means you have more experience with prior generations of the models. What I have experienced is that the AI has been getting better and better, and is making fewer and fewer mistakes.

Now, part of that is my advancements as well, as I learn how to specify my instructions to the AI and how to see in advance where the AI might have issues, but the advancements are also happening in the models themselves. They are just getting better, and rapidly.

The combination of getting better at steering the AI along with the AI itself getting better is leading me to the opposite conclusion you have. I have production systems that I wrote using spec-kit, that have been running in production for months, and have been doing spectacularly. I have been able to consistently add the new features that I need to, without losing any cohesion or adherence to the principals i have defined. Now, are there mistakes? Of course, but nothing that can't be caught and fixed, and not at a higher rate than traditional programming.