But there is a difference. One is what the airline is providing as part of its service and the other is someone who could choose not to impose smells on others and does anyway. I mean, you may not want to listen to PA announcements by cabin crew about welcome to our Executive club passengers and onboard shopping, but it doesn't follow that it is fine for any and everyone on the plane to bring their own microphone to thank their Mum and Dad for their Oscar and explain why since everyone is listening to them they should buy this new fabulous insurance policy in case their pet turtle has their lettuce stolen by the neighbour's slug. The airline has a legitimacy to define the flying conditions of all its passengers, individual passengers do not have that same legitimacy to define the flying condition of everyone else around them.
And even if you forgot about that fundamental difference, it wouldn't follow that adding more smells to existing smells would be fine. It would be like saying "oh well there is one person shouting on the street so I don't mind if there are 200 drunkards shouting", or one guy is listening to their music outloud so it makes no difference if everyone stops using earphones and imposes their own music to all others. It's not the same, effects do accumulate, and any one of us with a remotely sensitive nose who has flown US domestic Y dinner flights knows what I mean.
I do however, fully agree with you that tastes in smells are idiosyncratic, but that's why I (and I suspect many others) are not saying "we don't want McDonald's food smells but feel free to bring your tin of sardines and your Stinking Bishop", but rather "if everyone could choose food which does not smell strongly and does not make a lot of noise eating then all would be great" (
81romeo I think your Haribo are safe!
).
By the way, while many seem surprised at the argument, that one shouldn't really have to smell other people's food, many of us will have seen this enforced for years. For instance, I remember when I was a student, there was no problem bringing food or water when we had exams but if anyone brought anything smelly (most definitely including any hot food from McDonald's, cheese, fish, and more) or anything unduly noisy (apples come to mind), or anything that could lead to leaks, dirt and other incidents, it was confiscated and discarded immediately so as not to disturb the other candidates. I personally think that this was entirely sensible and good practice