"Critical" projects and volunteer maintainers

I understand the point of saying that 'pip' is 'tied to PyPI', but technically that's not true, it's just the default package index. Thousands and thousands of developers use other indices every day with 'pip', and it's quite easy to configure 'pip' to use a different default. It's even possible to specify additional index URLs in requirements files, although not on a per-package basis so that carries some risk.

It's basically the same situation as all of the other 'dominant' open source forges and repositories; all of the tools can talk to *any* forge or repository, but users don't want to have to take time to configure them so they just use the default ones.