There are many, MANY islands scattered around Earth's oceans. Not all of them have the resources to be self-sufficient, so any inhabitants have to import goods from somewhere. There are two options: either each island is its own country, or some islands belong to some other country. Given how easy it is to navigate to most islands (some of them are in harder-to-navigate straits), it doesn't make much practical difference whether the owning country is close or far away.

So no, as a general rule I can't agree. I can certainly agree that there are some rather silly cases, but it's just not practical for all islands to be self-governing, so I can't agree with the general rule you propose.