The reason why you can't just reject modernity and bunker up with an ultra-nationalistic dictatorship of sorts, is because the tech/system gap between those nations and technological nations will be like tribal men with sharp sticks and no written language vs current modern civs.

No point picking the ideologically pure faction if they can't keep you from subversion/slavery in the near future. And the isolation argument is weaker by the day.
Such is the geopolitical reality during the concentration of power/tech times, so we work to end those times quickly.