Interesting links man! Ive always though of that whole "break-in" thing as bs but the real reasoning behind the easy break in in my mind had to do more with allowing the bearings and all moving parts create their shape and wear safely until they had their final clearances which they would for most of their useful life. In reality they're clearances are so close to perfect that wear is almost none and identical its entire lifetime so that more of a thing of the past Id say. Not saying it doesn't happen, but not like new factory motors made in the 60s-80s!
Plus nowadays, almost all mfgs test the motors themselves and do MOST OR ALL of the break-in before we even touch the car! They've essentially removed all the room for error and simply recommend an easy few hundred miles for "peace of mind" if you will. I dont think they'd allow a chance for owners to actually ruin a motor not they could anyway as todays technology is so advanced. The machining is almost perfect and they measure to 10,000ths of an inch for clearances. Id say most new cars have near perfect seals and there is really nothing to break-in.
People who drive easy for some miles in reality are just trying to knock down an unlocked door. Eventually they'll get into it like they were going to anyway haha. Just delaying themselves. I honestly have no doubts or worries in modern engine manufacturing, Im going to be beating on mine the day I get and do it with a smile