I suspect anyone can call themselves a marine surveyor.
My own point of view is surveyors are creaming it by pandering to the middle class buyers' obsession with getting someone to tell them everything is fine, or maybe coming up with a long list of trivia to help knock a few £k off the price (whilst not actually carrying the can for their precious advice). Just buy a boat and enjoy it, is my (casual) approach. Whatever the survey report might say to put the fear of god into you, if you ignore it I bet the boat will still be floating in 20 years.
Just my personal experience and opinion. Other opinions are available.