It’s giving you an idea of what Claude is capable of - creating a project at the complexity of a small compiler. I don’t know if it can replace programmers but can definitely handle tasks of smaller complexity autonomously.
You are incorrect. You can not conclude something of lower complexity will not stump it.
"autonomously" I couldn't agree with, I use it regularly for 100-200 loc size stuff, I can't recall it ever being right the first time.