There is absolutely no evidence that you need a single large airport to be successful
Well aside from this :
Ireland - DUB (restricts BFS)
Germany - FRA / MUC, OK that's two but FRA is waaaay ahead
France - CDG
Netherlands - AMS
Switzerland - ZRH (GVA still smarts at only one LX GVA-JFK)
Austria - VIE
Denmark - CPH
Sweden - ARN
Norway - OSL
Portugal - LIS
Dubai - DXB
Qatar - DOH
Abu Dhabi - DOH
ETC ETC
They all have one thing in common. Large airport, usually capital city, a country mile ahead of local competition with a based legacy network carrier or alliance member. I get the impression you have a personal beef clouding your judgement on a fairly obvious market truth.