They really are a result of lazy operators. I dont know which is worse; salt motors, or the ones that sit in unfinished basements, barns, sheds, or better yet, under a pine tree for 10 years.
At least the salt ones are being run on a fairly regular basis.
I use my Etec in salt throughout the year and flush after every use (run in the barrel for 10 minutes on fresh water, hose down, and bomb it with WD-40 at least once a month).
Guess what I found when I pulled the gearcase to swap impellers and pull the prop? No salt, nothing stuck, and everything clear in the screw threads everywhere.
Other than some salt leaching through the head gasket, I dont see any white crystals anywhere.