[adgjlsfhk1]

The good news is that you don't need the C api nearly as much because you don't have to call out to C whenever you want performance. Also, the extent to which the python C api is documented has actually been a major problem for them since it has effectively frozen a ton of python's implementation in majorly detrimental ways (eg the GIL)

[patrick451]

Calling out to c "because you want performance" is only only one dimension of the issue, and assumes that your main application code is written in python or julia. In many cases (e.g., robotics), application code is written in c++ or c, and python bindings serve as simulation harnesses and visualization tools. Pybind11 is absolutely brilliant for this. The last time I looked, similar tooling for Julia was substantially less mature and definitely didn't look like something I'd want integrated into a production workflow.