Hi Paul, I requested your review because you helped with a similar PR few months back: #123337

To explain my motivations a bit:

I'm trying to be extremely careful about adding pathlib features I might later regret. It's already happened more than once while I've been maintaining pathlib 🙃

In this case, the implementation uses WritablePath.mkdir(exist_ok=dirs_exist_ok), but I'd like to remove the exist_ok argument because it implies readability, whereas WritablePath is otherwise write-only. Maybe this is solvable some other way, but for now I'd quite like to play it safe.

Hope that makes sense, thank you.

Looks OK to me, and I agree with your reasoning. Until we know how people are going to use the new extensibility, it's better to keep the requirements minimal. We can add functionality later if it's needed, and 3rd party providers won't have a problem with it.

Excellent, thanks for your help :]