Training clearly improves operator capability. Whether the operator uses that new capability is another matter. Rarely are there arguments where the truth lie between the extremes more than this. Good training would undoubtedly reduce accidents. Just think about the basics of red and green navigation keeping boaters off the rocks. However, there are many people who are untrainable or just won't care about what they were forced to learn.
Yes, the "good" being the can of worms. To me, "good" implies more than quality instruction and includes training like you get at good ASA certified programs. It also implies that performance standards are met and failure is a possible consequence. Can you imagine any state instituting a boater education, taining and licensing program in which people actually fail to qualify?
I guess I have just become cynical about this, but there is a difference between education and training. Using the pilot example, one can read the books all day long, but without "real time in the cockpit training", one does not become a qualified pilot and until a certain number of hours of such experience is reached, may not carry passengers for money.
Meanwhile our macho young man blasts off on his 14 foot overpowered ski boat and, well you know the rest. He may know; "speed kills", "don't drink and drive", "pay attention to the road" and "you are responsible for your passenger's safety", but he is caught up in the thrill of the moment and lets all that knowledge go.
By the same token, how many young men have grown up under the tuteldge of their fathers and can take the family boat out for a safe and enjoyable voyage? Probably a few here on sailnet.