I don't disagree with the principal but if the insurance company asks if you are the "registered keeper" and if your name is not on the V5 then you cannot answer "yes". You may be the keeper but you are not the "registered keeper".
It may be true that you SHOULD be the registered keeper based on the guidance from the DVLA but if your lease company will not put you on there, and most won't,like in the Ops case, then what are you suggesting he should do? lie?
Here is an example from Money Supermarket not much ambiguity there. it is not asking who reads the car a bed time story it is unambiguously asking whose name is on the official document.
View attachment 933877