Yes I agree.

So far, the only reason that I have heard of for requiring proof of insurance is for regattas with international competitors because they can leave the country and not be touched.

Even so, I personally know of a very famous Swedish Olympic medalist who skipped out of a high speed port starboard crunch and refused to pay damages. So even though he had liability coverage... it doesn't mean that you will be covered. S had to use his own insurance and pay the 800 dollar deductible...