It’d be useful to provide the context for that advice: when writing C extensions and macros, to avoid clashing with the CPython codebase.
Given that: if everyone standardized on this other prefix, wouldn’t they just start to clash with each other? It seems like the right thing to do is for each project to try to pick their own unique prefix, to the extent possible.
Yep, you are right, but I did not suggest to use Yp as a prefix, I suggest to use it as a way to refer to using your own prefix. It’s just a shortcut to say any prefix except Py.