The idea behind a MEL is everything has to work correctly unless it is covered in the MEL.
Or other ATP (Approved Technical Publication) such as the AMM or SRM.
Gawd I'm being pedantic today, sorry.
An example of a seat inop.
A330 electrical control, the fore-aft drive motor has a tendancy to fail in a way that it runs on when the switch is released. The result is an annoying whine for several seconds each time you move the seat. Seat operation is not affected in any way. Most pilots will accept it and report into main base where it will be attended to as required. On a line station there is only one option-MEL. Result is deactivation of electrical control (CB tripped) and the pilot will have to move the seat manually. Only slightly more annoying than a whining seat.
One could argue that the motor running on represents a possible fire hazard I suppose.
Horses for courses as they say.
