England, the home of "English," is located on a small island. (Three other English speaking countries, the USA, Canada, and Australia, can be considered to be located on LARGE islands.)
To get from the island (Britain), to the rest of the world, it is necessary to travel by sea. This was particularly true in the 18th and 19th centuries (when much of our modern vocabulary was developed) before the age of air travel in the twentieth century.
Most of what the country was about was getting goods and people to and from the country BY SEA. If President Coolidge said, "The business of America is business," he might have said, "The business of England is shipping." Hence, "naval" and "nautical" issues were pre-eminent in the life of Britain (and to a slightly lesser extent in the other English-speaking countries), and that's why a lot of English vocabulary/expressions is connected to the sea.
Under the circumstances, sailing wasn't a "highly specialized profession." Instead, it was part of the "mainstream" (pun intended).