What, precisely, are you saying is not true? You need a decentralized consensus mechanism in order to solve the double-spend problem, unless you've come up with something novel.
Having said that, I think that if these things are so obvious in your opinion, you haven’t considered real world scenarios.
People tend to respond that smart contracts are a solution. I personally think they will always contain bugs and are too complicated for the average person to vet.
In any case, I really wasn’t saying I think the whole subject is trivial. Pinky promise.