M_Boats: silicone

I have often heard that using silicone to bed deck hardware and ports on fiberglass boats is not a good thing to do. Recently on this site Bob Eeg also made that point. What is the thinking behind that? I know several people who have worked in boat building factories (Compac, Hunter, and Irwin to name just three) who recommend and use silicone for bedding hardware on their own boats. Beckson Ports specifies silicone for bedding their ports. Confused -- looking forward to reading thoughts on this. M-17 Atta Baby