"Culler" is not, because anyone who does spell it that way is immediately corrected, and their written spelling is rejected by the person who receives it. We can describe these rules of that interaction as descriptivists, and still conclude that something is wrong or incorrect.

Orthography isn't really a part of grammar, so it's easily possible for natives to make mistakes when writing that might make a word difficult to understand. It's much harder for spoken language to be misunderstood among the population that a native grew up in, because the words they use don't come out of nowhere (despite the old prescriptivist argument that you can even see in this thread saying "I'm just gonna call houses xytuis because any words are ok!") Obviously now with mass communication people pick up language from all sorts of places, so you might have words be unrecognizable even within a locality.

Even so, an individual's (native) idiolect can't really be "wrong" to descriptivists in the way orthography can. It'd just be chalked up to differences from the local language or dialect.