I agree.
For me, joke is something that should not be taken on a serious note. We often add 'just joking' if we don't want to hurt someone with a blatant truth. But in an ideal world (let's not argue if this is an obsolete concept or not), truth should never be treat lightheartedly. A truth is always a serious business unlike a joke. It can be a surprisingly funny truth, but never a joke (according to how I define a joke).