And where should these airlines train?
If I work for an airline based at a 'big' airport with no slots, then when it's time for circuit-bashing there simply is not the capacity. If my 'big' airport has night restrictions then this definitely forces me elsewhere.
Most airlines will use airports such as MSE, PIK, EMA, etc. for training because a) It's cheaper and b) They can't use home base.
I totally agree with the frustration of people living there, but only feel sorry for the few who were living there before the airport was built.