Anyone could just change username/organization and break thousands/millions of build.
In Python, we don't say "we don't host packages on a proprietary platform", we say "we have absolutely no clue where they are hosted and nobody audits them anyways, and we don't enforce package signing, and we'll just build from source with no build isolation what so ever, unless you remember to specify an obscure command-line option when installing... and have a nice day!"
Package signing is, well... I suppose that's another lesson from the '90s people will learn about soon enough. With a web of trust as broad as python or npm you'll just have everyone running around with signing keys and "trusting" any key they come across because none of it is built on personal relationships. When Archlinux asks me to confirm adding package keys, what am I going to do? Say no? I don't know these people, but I want my shit to work.
With systems like Python, I'd imagine that a solution to web of trust would be that some group of developers would organize a curated set of packages. So, for the cases where you need better security assurances, you'd use that. I mean, of course there's no guaranteed solution for the web of trust, but, in practical terms, something like that would be good enough for regulators.
There's already stuff like NumFOCUS. They don't particularly focus on the technical side of things, or endorsing more secure practices, but, in principle, they could. Maybe there will also be others once we have been bitten more times by some security breaches.
GitHub redirects you to the new name in the event of a rename and you look up the old one.
so it's not quite as bad as you're imagining but still not great.
fortunately GitHub is starting to require 2FA for very popular projects (starting with NPM) because of supply chain attacks like what you describe.
