BahrainLad, quite correct! Each one of those you have mentioned is working towards a COMMON goal - to get the aircraft airborne. And only ONE person is able to achieve that, the PILOT.
What you have done, is to RE-INFORCE my point that MANY, MANY other people are dependant on the pilot(s) to realise (all of) their efforts, by using his abilities.
Take away ANY of the individuals you have nominated and the airline will not be grounded (with the exception of the purchaser)...sorry spannersatcx but if you don't sign an aircraft out, it is still possible for the commander to override the MEL - if he considers it necessary!
NONE of the job classifications mentioned by BahrainLad are NECESSARY to operate a commercial aviation operation.
Flybygirl, we can do it [change the oil, the tyres, clean the windscreen, etc...if required. But what's the point of having a dog, and barking as well!!??
Show me an airline without pilots, and you'll convince me!