I get Dave’s rationale - it’s the same principle as Aldi, Iceland, Lidl prospering over the last few years because they were more nimble with their smaller ranges and stores than the ‘Big 4’ who were lumbered with huge volumes of floorspace that was no longer wanted or needed. But in this case his application is flawed as he is looking at it one dimensionally.
The big thing he misses is location - if we assume runway length isn’t such an issue Luton is also quite small but has stronger existing non-passenger activities and is geographically better located as it’s reach is wider.
The other is how practically such a scenario would play out - in reality the giants of Gatwick, Heathrow and Stansted would collapse. This would allow a new more nimble owner to take them on at a discount, turn what’s not needed into housing and retain a single long runway and terminal for the 30 flights.