I'm not sure what goes into the decisions package maintainers make in terms of which packages to include in the OS repository, but, in my experience with python

I'm not sure what goes into the decisions package maintainers make in terms of which packages to include in the OS repository, but, in my experience with python applications, most dependencies we needed could be found in the OS repository or some other supported package repositories (for RPM, repositories like epel or rpmfusion). The few we weren't able to find weren't that difficult to package and add to our internal package repository. But this also brings up the issue of vetting dependencies. If you're pulling in a dependency that pulls in 10s of other dependencies (direct and indirect), it gets difficult to vet them. PyPi and npm have already had issues with malicious packages being uploaded. On the other hand, I haven't really found the large number of dependencies being an issue for python packages available in the OS package repositories, and I'm not aware of any incidents with those repositories unlike PyPi and npm.