In http://docs.python.org/dev/extending/newtypes.html, you can read:

“To enable object creation, we have to provide a tp_new implementation. In this case, we can just use the default implementation provided by the API function PyType_GenericNew(). We’d like to just assign this to the tp_new slot, but we can’t, for portability sake, On some platforms or compilers, we can’t statically initialize a structure member with a function defined in another C module, so, instead, we’ll assign the tp_new slot in the module initialization function just before calling PyType_Ready()”

But the thing is, we ourselves (CPython) do exactly what is discouraged here, both in built-in types and dynamically loaded extensions.
So is this piece of advice still necessary?