As far as I understand, this is purely a result of lack of maintainer resources. Apparently, nobody has been bothered enough by this to contribute the relevant changes.

Keep in mind that all of rustc and libs development takes place on Github.

Yes, unfortunately it is true. Sad, but I could live with that.

What in my opinion is unacceptable is that it requires you to give permission to "read your organization and team membership and private Projects".

I made a separate GitHub account (weinzierl-trusted-publisher) for crates.io which is far from ideal, because it works completely against the idea to build trust for a single unified identity online, but ¯\(ツ)/¯.