I'm certain I created a tag wiki for jehovahs-witnesses, but there isn't one now. Is my memory deceiving me, or did someone delete it? And, if so, why?
In general, no they will not just disappear. In fact they are versioned so that you can see the history of who changed what. Obviously I don't see any changes from you in there.
Perhaps you changed a similar related tag wiki that later got removed or merged into this one or some other action?