Bearings rely on a hydrodynamic film, in other words as long as there's oil pressure and flow past the bearings, the journals don't touch the bearing. Except of course during the small amount of shear during the power stroke. A cylinder relies on splash lubrication, and the oil on the thrust surface of the cylinder skirt deals with far more shear forces than the crank bearing ever will.
Low viscosity is good for reducing pumping losses, but higher viscosity sometimes but not always has higher oil film strength, which is good for lubricating things without oil pressure(ie pistons,gears,chains etc).
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee