But it has become more necessary and useful, so even C programmers better get used to it (and some tooling to help catch most mistakes).

>so even C programmers better get used to it

Or else? It's not like they're not trying their best - or don't spend the level of effort that they and their companies are willing to take...

I guess it would have made more sense for me to say "Python C extension developers".

I don't find multithreading in languages without particular support easy at all, but I have become better at it. It is possible and sometimes necessary. It seems like the prevailing attitude in the Python ecosystem is weird, a kind of sour grapes thing, i.e. "Python doesn't have good multithreading support, but multithreading is ugly and error-prone anyway and the alternatives are almost as good or better".