This crypto-signature approach is already used by the Apple MFi program, which has made it difficult-to-impossible to sell counterfeit and/or unsafe Lightning devices.

You're worried, I think, about poor-quality devices that aren't malicious, just incompetent - or poor-quality cables. (I'm already willing to carry my own cable - I already carry a USB-A data blocker around, but USB-C data blockers don't seem to exist.) I think that can be solved without cryptographic authentication, with the standard approach of having a certification organization like UL or the USB-IF themselves investigate cable/charger production and test them. It seems the major problem here is with Amazon listing cables without showing whether they have certifications (or checking whether certifications are forged), and that's a general Amazon problem with poor-quality hardware and counterfeits.

This article is talking about autorun, Stuxnet, etc. so I think they're focusing on the latter. If the USB-IF wanted to use digital signatures to authenticate cables I'd be more on board, but if they do that, they should just be authenticating cables, not devices. (A cable, I believe, can be engineered to just cut the circuits if a device tries to pass too much voltage, or is wired backwards, or something.)

They do -- I carry one one of my employees made in our lab. Search for "usb-c condom" or "usb-c data blocker" and you will find several offered for sale.

Incompetence is scarier than malicious actors imo, and expecting users to carry USB condoms around seems like a bad idea.

Apparently not according to the Chinese, who made the first clone (based on an 8051 microcontroller IIRC) within months of the official release. They're still in an ongoing cat-and-mouse game with Apple.

By controlling issuance of permission to use the connector, Apple is able to prohibit non-compliant products from becoming widespread worldwide. (And even China just last month declared their intent to make IP enforcement viable, which further strengthens Apple’s position with respect to MFi.)

The USB folks appear to believe that if they introduce a similar licensing arrangement for USB, they’ll be able to refuse licenses to unsafe implementations to deny them access to the worldwide USB market. MFi still works today, so I certainly don’t blame them for trying.