I suppose it must be a thing that while crates.io does disallow this, there's a possibility that there's a private registry out there that does allow it. That's

I suppose it must be a thing that while crates.io does disallow this, there's a possibility that there's a private registry out there that does allow it. That's the only reason I can think of for why they haven't just made it treat them as interchangeable in Cargo.toml files.