Who is "they"? PyPI is an index; it doesn't control your installing client.
(This is a larger issue - or feature, depending on your perspective - with Python packaging. But it's important to understand that PyPI itself can't force `pip` or any other client to pick any particular resolution order between indices.)
(This is a larger issue - or feature, depending on your perspective - with Python packaging. But it's important to understand that PyPI itself can't force `pip` or any other client to pick any particular resolution order between indices.)