Nowadays, engines fail rarely due to high tolerances and better oil quality. Most car land on the junkyard because of electronic failures the owner doesn't want to pay. That's why you can get so much good engines at the junkyard.
I don't see evidence for the argument that auto industries extended the oil service intervals and shorten the engine's life. Auto industries shoot their distributors and dealers in their back if they 'rob' them their income. Competition is a better explanation here. If make A extends the intervals the other makes have to extend it also because the customers are comparing and choose the one with lower expected total costs of ownership.
If it's possible now why did they send us every 6k miles to the dealer in the 80ies? Ok, 20 years are a long time of developement as todays oils are much better in the meanwhile, mainly because the auto industry required higher quality for their longer service intervals. If you change a today's high quality oil every 3k miles like a 20 years old dino stuff it's still a waste of money.
Just my two cents.
