Article on possible reason for headgasket issues identified?

Very interesting article talking about the cause of the headgasket issue. I always wondered how anyone could call the Toyota engines reliable if we had this issue on the CTs and the Prius. Apparently it happens on other model engines as well. According to this it is the coating on the head gasket. The coating is only on the edge of the gasket instead of across the whole surface of the gasket.

https://www.yahoo.com/autos/ownership/articles/toyota-head-gasket-failures-point-123000166.html