Actually it's not about catchment population, that's a terribly simplistic view.
And to counter your claim, Ryanair operated to DUB from LBA and EMA.
EI Regional came in and started EMA and LBA. Both EIR and FR continuing to do well on the route. According to your argument, the EIR presence should have divided and conquered. It didn't …
Then, EIR launch DSA. DSA is doing well, and so is EMA and LBA. In fact, there have been frequency increases for this coming summer. FR continue to operate …
As many others seem to agree, there is a market for both LBA and DSA. Which should be the dominant airport is another argument, but they are both growing and developing and will continue to do so, and as an airport is a catalyst for economic development, both of them developing will only seek to strengthen yorkshire, not weaken it.
I feel I've said enough on the subject …
Great news about the new routes from FlyBE at DSA, I am sure they will do well, and with the link road now up and running and phase 2 on the way soon I see a bright future ...