Sorry, but "Surely you can see the flaw" is not meaningful contribution to the discussion. It's just a passive aggressive way of saying "you are wrong so please think until you realize the superiority of my opinion".
There is two simple truths.
1. If a group decides that it doesn't want to be ruled by a certain body, it's hard to legitimize the continuation of that rule.
2. If any group, especially very small ones can refuse the ruling body, all big groups will ultimately split down to individuals with no rules at all.
Democracy only works when balancing these truths. Trough opposition in parliament, minority rights, local and regional governments, regional independence and so on.
I.e. the whole situation in Catalan is blowing up because the reginal independence wasn't granted (or not enough in the opinion of the Catalans). Look at South-Tyrol in Italy for an example where things are working better. Even the American states are a good example - liberal, rich California wouldn't accept Republican rule without the independence the states have.
Surely you can see the point I'm trying to make?