No one is blaming PG&E for all wildfires. We are blaming PG&E for the wildfires THAT THEY CAUSED. These fires could have been prevented if THEY BURIED THEIR POWERLINES back in the early 2000s when it was far cheaper and like they promised. They instead decided to ditch that and instead buyback stock and pay lucrative dividends.
Burying powerlines would 100% prevent wildfires which were caused by sparking or broken power equipment, which has been the documented reason why several extremely large and fatal wild fires were caused by.
To have a fire you need a spark, air and fuel. The air is there all the time. The fuel is there whenever there hasn't been a spark recently. And power lines aren't the only source of sparks.
Once the fuel is there and accumulating, you're playing roulette to see if you're going to have a smaller fire now or a bigger fire later. There is no option for "never have a fire again" in those areas, and the second option isn't inherently better than the first one.
They took a risk by underspending on upgrading, and we as Californians are paying for them paying out their shareholders.