Did a license ever stop an accident on the road?

I'm sure it has, but I don't think it's appropriate or feasible for
boats. It's just a tax. Cars require a test, minimal though it is.

Driver's licenses are just a tax too, along with being the defacto national ID
card.
In my state you can renew by mail pretty much after you are dead. My mom was 86
when she mailed in her 4th 6 year renewal, from a nursing home and she died
before it arrived. The picture on my license looks like my high school yearbook
and there are so many renewal stickers on it I have a hard time getting in in
the wallet slot. They still cash my checks tho.