I think the argument is, that you will only remember activities, but not idling. So if you're busy during the flight, then you will remember that. But if you do nothing at all, then you won't remember anything. If you don't like flying, that's an advantage, because you won't remember the flight.
well, I have experienced similar things myself. When I find myself in stressful situations, I just switch off my mind and go forward, because I know that that way I will eventually find a solution to my problems. For example when I have a lot of work to do. If I start doubting, I won't get anywhere. So I have to switch off my mind. And in fact, in retrospect I rarely remember the difficulties that I went through. Maybe, though, that's just my personal experience. Maybe for other people it doesn't work that way.
I do like to travel just listening to music idly, doing nothing else. That’s pretty relaxing for me. Even then, though, I hate planes and airports and the air pressure and how much you feel like a fucking piece of inanimate equipment the airline is just shuffling around for money.