This is a bit like saying the 2020 Beirut explosion was 100% caused by the carelessly dropped cigarette (or whatever started the initial burn; nobody knows).

Well yes, in the sense that someone somewhere did something that triggered the cascade of effects that produced the boom. But assigning "100% of the cause" to that individual just lets everyone else in the chain escape blame.

If it isn't PG&E this year, it will be something else next year. Or the year after that. Like the LNU complex, it could be simple lightning.

Which is not to say that PG&E doesn't bear some responsibility, but "100% of the cause" is too reductive.