I believe that the general understanding is the acidy nature of the oil will eventually pit the bearing races, if it just sits for long periods of time. Which I also understand is why low mileage garage queens are potentially 'more prone to failure.' If you run the engine regularly, it helps to burn off the moisture that accumulates in the oil. And slowly leaks/forces fresh oil into the bearing and past the 'seals' of the sealed bearing.
Looking forward to corrections for any mis-statements.
