What happens if that centeal authority becoms subverted (as many people here would argue is the case right now)?

Doesnt that single point of failure indicate a weakness?

Values are your culture. The Nazis were elected and supported (at least initially) so you are right some what, but the answer is multiple countries.

But a country without a culture and without shared values is a sled being pulled by dogs in different directions and not a real team (as many people would argue has been the case for quite some time).

You need common values to work together to achieve goals. That's what a country is, people working together. When you don't, you just become tenants with passports.