It's more formally known as intentionality fallacy. You can say that the opposite of this fallacy, particularly in literature, is called Death of the Author. It's based on an essay by a literary critic that you can easily find online.
The gist of it, especially when used in forums like this one, is that authorial intent, or Word of God as a term often used in battleboards, is not the end-all-be-all absolute objective interpretation, explanation, or fact about a fictional work.
That's not to say that authorial intent/WoG is ignored or disregarded, but that the fictional work itself takes priority over the words of the author, though there can be exceptions.
To explain this concept outside the confines of dumbass powerscaling, take a look at the Cthulhu Mythos, which is quite popular in this website. Its author, H.P. Lovecraft, was more or less a raging bigoted racist for the majority of his literary career, which definitely influenced his writing as one of the biggest innovators and most influential horror writers of all time.
Does that mean we can only view Lovecraft's works as reflections of his racism? No. But it doesn't mean that the racism in his books have to be ignored either.
Just that you can look at the Cthulhu Mythos without worrying over whether Lovecraft was having some thinly veiled racism in it or not.
addendum: Lovecraft's bigotry is also at times exaggerated, so sometimes certain readers actually circle back into interpreting his works as more racist than it actually is (see, Shadow Over Innsmouth). So you can see how complex literary analysis can be.