Don't blame them! Back when they put those screws in, rain was less acidic, so the electrolysis (if any) was less pronounced and took much longer to occur than it does now. How could they have known how bad it would get? Besides, why would you want to ever change your spreader tips? They probably didn't have 5200 when they built the boat, and were maybe COUNTING on electrolysis to make sure nothing ever got loose up there. Their way of trying to save future owners any hassle or additional costs without relying on futuristic goop.