That point being noted, nevertheless that does not mean that it is governed by the principle of "insurable interest." It arises from carrier business practices and rules.
Insurable interest means that you cannot insure some thing or someone where you would experience no loss if the person or property were lost. The beneficiary is not the insured. Again, I am not saying that there are not other rules or principles that they rely upon in regard to the naming of beneficiaries.
I was in the same line of thinking, that the beneficiary did not require any insurable interest, simply the policy owner (who may or may not be a beneficiary). I looked it up. Turns out, some states do have laws about the beneficiary having an insurable interest as well, when the policy is issued. Nothing afterwards.
Obviously, some states were trying to shut down some insurance scams. Probably didn't work, but it was a try.
Learned something new here.
Dan