A lot of good points made here. Certainly things that get there
oil slung onto them from the crank do not benefit form any type of pre-oiling.
I too spin the engine to build
oil pressure before turning on the ignition, but I have no delusions. It takes no load off of the valve train. Without pulling the plugs, it doesn't do a whole lot for the bottom end bearings. About all it does is take the shock of ignition away.
I have to agree with Blykins (it sure doesn't hurt anything). It doesn't solve every problem, but it does fill the bearings. It also has to shorten the time that it would normally take to sling
oil to the other parts. In short, every single part is going to see oil sooner.
Now I saw a newly assembled engine get drove around the block on assembly lube, as the oil pump shaft was missing. Although not disassembled and inspected, the engine had no ill effects.
It does bug me on starting an engine that has sat all winter. If I had $20K in an engine it would bother me even more.
BTW - the accusump sure does have an added benefit of supplying oil when the oil is slung away from the pickup. We know that can happen with these cars.