Ignoring the massive cost, legal hurdles, and the opinion of the residents/government/outside powers, if you could magically grant independence to certain territories or form new bigger nations from existing ones with no repercussions to yourself, what new countries would you create?
Please treat this as a non-serious post, let's not get into a massive political debate, those never end well.
That's why I didn't propose an anarchist vision. I do recognize the need for states. Just very very weak ones.
Nation states are a different case altogether though. You can have a multinational state. Sure, it is easier for a state to continue existing if the landmass it controls identifies as a single nation. That helps give it legitimacy.
I'd recommend reading more about nation states and why nations ≠ states.