The trouble is that the field is too broad. There are too many kinds of backpackers. Para-professionals in SAR are not backpackers, either, most of them (that I know) are not backpackers or day hikers. They use the same gear to different ends.

It is completely unnecessary to have that mental toughness if you go for a weekend, every other year or so. It is probably unnecessary if you go a few times a year. It is necessary if you intend to do the entire PCT or any other through hike to develop some measure of mental toughness, because the longer you are out, the more likely things will happen, conditions will change unpredictably or just the unexpected happens.

I do not disagree that I probably am mentally tough but it has absolutely nothing to do with backpacking experience - where it made a difference with me was after the initial return to backpacking, from whence I returned dehydrated, tick-bitten (and thereafter rash'd from knee to bellybutton), exhausted, blistered and pretty much mentally gone. The mental toughness came into play in the weeks following - when I decided to go again. Had nothing to do with the trip itself. It also comes into play in my career. It also comes into play in other areas of my life. I don't have to have it on leisure backpacks because the more important aspect of backpacking is proper planning, which I've got down pretty well.

People who are backpacking out of curiosity go away after they have an initial torture test. I wasn't doing it out of curiosity - but my particular geekness is in figuring out what went wrong and fixing it, whether it's a computer, a sewing project or other hobby. Figuring out how to backpack without suffering was my goal. I'm pretty much there.