That would be the preferred way to do it, but we got no traction from anyone at PyCon or on python-dev when we tried to get people to look at what's changed.

I suspect we haven't marketed the stable API well enough to have a lot of users, and the build tools still mark everything as 3.x-specific rather than 3-specific. Keeping it as a bare minimum interface has its value, but it's not unreasonable to expect that the functions available from the headers under Py_LIMITED_API are actually exported by python3.dll.