That makes sense from the consumer's point of view. But imagine you're a manufacturer, producing USB device controller chips by the million. Would you really be willing to spend tens of thousands of dollars to protect against a failure mode that can only happen due to some other company's extreme negligence?

Yes, but of course it doesn't matter what I think.

It's not abnormal to add protection that isn't needed when everything works properly. As noted elsewhere, the USB spec already requires resettable overcurrent protection, for example.

Tens of thousands of dollars total is far less than it costs a company just to moot the question.

Sorry I was not clear in my comments. The dollar solution is for some type of crowbar circuit. This is the most robust solution.

The 3-4 cents is for specifically, reverse polarity protection when somehow, a -5V differential is applied to device power inputs.

This cheaper solution only narrowly addresses this particular power fault, and no others.

I see! A dollar per port for robust protection against a wide variety of faults sounds pretty good to me, but I know that sort of stuff doesn't sell well when people compare primarily on price.

Do I assume correctly that a fuse for overcurrent protection wont act quickly enough to save the hardware in the event of reverse polarity?