I agree with some of what you say. But crossover does save bearings. How you say? You are restricting the oil to the number one main at the front of the block and feeding it from the oil passage at the rear of the passenger side to the front of the driver's side. This makes the number two main the front Main in the oiling on the passenger side. Therefore the oil is no longer having to make that 90° turn and then go on pass for the next Main bearing. Number two becomes the number one front feed. You are no longer going to take the chance of starving that bearing because the oil didn't want to make a 90° turn to feed it. So therefore the crossover tube does help save the number two and number four main bearings.
This is my humble opinion and I fully endorse it.
Remember I am talking hydraulic lifters here. If I was going solid I would tube the block and block the oil lifter Galley on the driver side.
