If your engine is worth ( for the sake of example) 3-5K to rebuild , and thats a simple motor, why would anybody put cheap oil in? or even waffle on good oil and regular changes?
why is bike oil more expensive ? for the bazzilion gallons of car / truck oil , they package a lot less motorcycle oil , its just production and packaging reality.
I have seen an oil related engine failure , they ran it out of oil. However as an indicator of engine quality , a kid came to a shop I worked in with a Honda 50cc mini bike that was squeaking while it ran, completely empty of oil, topped it up and I think it ran another deacade. 70's Honda was truley bulletproof