Well there are PC bricks, just not software bricks. I'd argue pouring coffee on your motherboard can brick it pretty easily. I think once the term became more widespread on mobile people used it for everything.
There was also that arch Linux debacle, where users with a certain motherboard mounted the uefi partition with write permission. Some motherboards were bricked that way.
Example: "I just loaded a buggy web-page and bricked my Chrome. LOL!"
You know. How the term "hacking" has come to mean just about anything these days. There are no PC-bricks, despite people trying to claim the contrary.