Yes, sailing is really safe if you don't count minor injuries such as bumps, bruises, and sore muscles.
With that said, look at the death rate per vessel involved, Sailing has a rate of 6 deaths per 69 vessels or about 10% of the vessels involved had deaths. While trolling had a death rate of about 33%. And being at anchor is about as safe as sailing, 27/211.
The data that is missing is an indication of how many boats or trips in each category. If there were only 69 sailing events and 6 deaths, that is pretty high. However, if there were 6,000 sailing trips with only 6 deaths, that is much lower.
Another number that would put this in better perspective is the number of accidents per type of registered boat. There are many more powerboats and kayaks than sail boats, so one would expect higher absolute numbers of injuries and accidents in powerboats and kayaks than sailboats. It is the rate of accidents that is telling.
I think sailors tend to be a bit more safety cautious and compliant with USCG rules than powerboaters. Except for Jet skis, how often do you see folks on power boats wearing PFDs? Compare that number to sailors, where many sailors wear PFDs when they leave the dock. Anecdotally, at least in the area I sail (Lake Ontario) the USCG seems to recognize that sailors are a safer bunch as they rarely conduct safety inspections of sailboats, but routinely conduct inspections of powerboats and jet skis.