By this standard we passed the milestone in the 60s when Lisp was used to build better Lisp compilers.

By a more honest standard we are still a very long way away from AI suggesting new ANN architectures, new approaches to managing RLHF, better training data, new benchmarks, etc etc. LLMs are nowhere close to being able to improve themselves.

It's not binary. Your example is recursive self improvement, just a weak kind because the productivity bump was small. But now we have AlphaEvolve which can likely come up with new architectures. The productivity bumps are much larger and will keep growing.