i mean i suppose it's like, i don't think that most GMs are flat out not interested in character backstory, but when a player brings a backstory to the table that they've premade, i think there's a tendency to be a little overinvested in a specific manifestation of the pre-prepared ideas, so they want the world to fit around their character concept rather than fitting the character into the world, and at that point it's the character that's the odd one out in the scheme of things.
you may complain that the GM doesn't care about your character's role in the world, but equally, in designing that character preemptively, how much are you showing you care about how they fit into the GMs world?