Somebody states that they think X because of Y, and they don’t say anything else (Y can be also a group of reasons). You show an analogy where Y would cause Z too (provided the logic is solid). The other party states that they think differently about Z - the reason doesn’t matter.
In this case, either Y isn’t important at all, or there is also something else besides Y, which is not stated. In other words, X is not because of Y logically.
