Lots of things on a boat needing replacing at or before 10 years old is the norm and to be expected if the boat has been used in saltwater even once. If always was used only in fresh water, normally at twenty years old no replacement issues are the norm. This is when using the same maintenance on both. Saltwater can and usually does ruin almost every manufactured major item/assembly it gets on as its corrosive action just keeps on eating away especially in joints and moving together surfaces where it can't easily be washed away.
In the Midwest where salt water doesn't exit, there's still a lot of 1950's outboards and boats (aluminum, steel, fiberglass, and wood) running and functioning just like when they were new and we see them all the time.
Cedarville/Hessel and also Spring Lake and several other places have annual large gatherings of and in the water shows with these very old boats and engines every year and only the exterior paint or rubber items have usually been redone or replaced.