I'm confused...you're saying that the regatta organizers should urge people to have insurance because people should have insurance. However, to require proof of it is crossing the line?

I don't even know what side of the fence I'm on regarding this topic, just trying to understand what you are saying.

In the big picture, regatta organizers are providing a service to customers (the sailors). Should this service include some assurances that everyone competing has a reasonable amount of coverage should something go wrong?