These latter I see as an example for how easy the idea of the nation is malleable. The Eastern separatists came into being and came to influence because of specific historic constructions, not because of a natural automatism. Under different circumstances, the separatist movement may have never gained traction, and happily remained part of Ukraine. That is why it's so vile of Putin to legitimate his war with a "Ukraine does not exist" retoric. With the same arbitrary arguments that proof that Ukraine does not exist, you could dismantle the legitimacy of every other nation, including Russia.