The argument for a hub includes these unspoken notions:
London businessmen will not do business in Timbuktoo if they have to change planes in Paris.
Non-London businessmen will do business in Timbuktoo if they have to change planes in Paris or London.
London businessmen will not do business in Timbuktoo if their flight is on a small plane from Stansted rather than on a large one full of transfer passengers from Heathrow,