True, a broken shackle at a spring is just as bad as any other time (and dangerous). Same with a rotted subframe that supports a control arm up front, just as dangerous. But to have your entire family in the car 300 plus miles from home when it happens, seems a little worse to me. But perhaps I’m wrong because to have a failure like that at anytime could mean another family traveling next to you could be in danger too.
Your last paragraph makes sense to me as well, the high rpm long trip could cause something to go wrong perhaps more than a short tripped, lower rpm event. When you’re pushing that 75 mph highway trip for 6-7 hours on end, yeah something could let go.
I do love high mileage vehicle though, and I’m always a fan of those cars/people that take those vehicles the distance, but I’d be selective on how/when I’d make those long trips in them. Just my opinion.