I don't at all disagree with that, actually. I do consider that a part of setup.py, but it rarely matters in practice. The python ecosystem doesn't have similar programmatic api specs compared to, say, PHP where they get together and rigidly define these things:
http://www.php-fig.org/psr/psr-7/
Not to say the PHP strategy is necessarily ideal (feels restrictive to me), rather just the comparison between the two. That's the sort of ecosystem that would make the abstract part matter more
No, no, Python very much does. PEP 0249 specifies DB API 2, PEP 0333 specifies WSGI, and PEP 3153 specifies the asyncio interface, for instance. If anything, I can think of more examples of it being done in the Python space than the PHP space.
Not to say the PHP strategy is necessarily ideal (feels restrictive to me), rather just the comparison between the two. That's the sort of ecosystem that would make the abstract part matter more