I think you can argue that an airline's profit margin is created by any single class of passenger or load of cargo. Economy passenger revenue is critical in the equation as are First, Business or cargo loads.

Returning to the OP, I do think that the views expressed on FT are skewed. People on here are obsessed with details that many others wouldn't care about or notice. People here get close to having a nervous breakdown if they can't allocate their favourite UD seat, or are not sure if they will have a flight with NF. I'm sure that most passengers don't get so stressed about these details.