I know that YA readers exist who don't give a shit about that stuff

Yes, they do exist. They just aren't as vocal as the readers who are involved in the shipping wars. My personal theory on why this is (just like you alluded to) are the "immature" readers focus on the twu luv aspect and cream scream all over it, while the more "mature" readers can recognize that the oppressive government needs to be overthrown. It's all about priorities.