Nothing wrong with PC boards, it's the damn shitty op-systems that crash them out.....obviously keep away from windows, but most high-end industrial gear is using a linux kernal these days which is rock solid, and the other 1/2 go exclusively embedded....
However, nowadays they're a hybrid of embedded & linux running the show, but the boards themselves are FINE.

A motherboard can die (electronically) just as easily as an embedded board, and i've seen some shocker embedded RETAIL boards that just shouldn't be marketed to industrial markets, and yet they still get installed....