that appears to be because the maintainers have chosen not to release any files
https://pypi.org/project/graph-tool/
that's not a limitation of pip, that's a limitation of the maintainers of graph-tool
https://pypi.org/project/graph-tool/
that's not a limitation of pip, that's a limitation of the maintainers of graph-tool
EDIT: But let's not pretend getting cibuildwheel going for every supported variant of PythonMajVer/OS/(32/64) bit is an easy lift for small open source projects. Conda is still more ergonomic than this, although it's slowly dying because big projects have the manpower to stand up and maintain the CI pipeline for PyPI, so Conda is less and less necessary.