Everyone on Earth has a petty identity. If we allow secession just so every self-identifying group can 'rule' themselves then we encourage those petty identities when we should be discouraging them and instead encouraging universal humanism.
IDK where are you getting this ideas but is mostly the opposite. PP is disrespectful about everything but that doesn't mean that there's no autonomy, there's a reason why every region has an "autonomous government" and are called "autonomous communities", basically because they have that autonomy.
More: https://en.wikipedia.org/wiki/Autonomous_communities_of_Spai...