True, I am fortunate that I sail in less crowded waters, I get quite excited when I see a ship. On a crossing from Sark last year we had four hours of 50m visibility and checked the AIS every 20 mins, not a ship in 25 miles! Just before we entered the shipping lanes the fog lifted and the sun came out we crossed the lanes without spotting a ship and had a cracking night sail back to the mooring.I believe that yachtsmen occasionally managed to cross the Channel or North Sea before the advent of AIS and sometimes came to no harm. However, as an adjunct to radar in restricted visibility it is very useful so long as its ,imitations are recognised. Although this is an infrequent occurrence for me, its chief function is to increase the enjoyment of sailing with my wife, who is more apprehensive of big things than me. If I can see a ship on the screen ten miles away and tell her that under present conditions the ship will be 1.6 miles astern when we meet, that is a great reassurance for both of us, since this is not evident when the ship is first seen over the horizon. It also makes complex situations much easier to sort out, as happened to us when approaching Blankenberg across the entrance to Zeebrugge this year, with a number of ships going in different directions. It was simple to click on a ship and see which port it was heading for and make allowances.
This is just one example, but as I say, it increases the enjoyment, which is why I go sailing.