Okay, so an arsonist sets off a massive wildfire. Should they not be found at fault? Surely the fire would've barely burned at all if it weren't for the conditions.
Nobody disputes that conditions were a contributing factor. On the contrary, that's why it was more important than usual to prevent sources of ignition as much as possible. It wasn't a lightning strike, it wasn't a hot muffler, it wasn't arson, it was PG&E's equipment that ignited the fire that destroyed an entire community, and that equipment failure was the direct result of their chronic poor maintenance.
I think the comments here are quite civilized all things considered. PG&E has a long history of poor equipment maintenance and has been the proximate cause for numerous environmental disasters. They are responsible for the deaths of over a hundred people over the last few years, the endangerment of thousands more, the displacement of tens of thousands more, and the destruction of multiple communities.
No action currently being taken against them is inappropriate under the circumstances.