What is "prophecy"? Throughout all of scripture there must be a common definition of what "prophecy" means. From the prophets of the Old Testament to "prophesying" in the worship centers of the Early Church, the word prophecy never changed meaning. It was not until recent times that prophecy has taken on a meaning different than the one reflected in the Biblical tradition.
There, in fact, is a definition of prophecy consistent throughout the Bible. "Prophecy" does not mean to foretell the future; prophecy means to tell-forth God's truth. Prophecy is not a crystal ball with which we can see future events; prophecy is the proclamation of God's word. In other words - it means to preach God's will and truth. We see men and women "prophesying" in the NT.
In the OT, prophecy worked much the same way. Ironically, those who propose a definition of prophecy that it predicts the future, ignore the vast majority of OT prophecy. Most OT prophecy is EX EVENTU Prophecy (literally, prophecy after the fact). Most of the telling of events by the prophets, actually happened AFTER the event occured. For example, they would explain WHY something happened (e.g., because Israel did evil in the sight of God). In the rare event where a prophet would tell of an event in the future, it was almost always conditional - IF Israel did something, THEN God would bless/punish the action, whatever the case may be.
In the Bible, the purpose of prophecy is to speak the word or message of God.
People who call themselves "Prophecy Scholars" are anything but. They do not recognize that the purpose of prophecy is to make God's truth known, not give an outline of the future. Yet this is the common defintion of prophecy throughout the Bible. The prophets are charged with making God's truth and will known - not seeing the future like some kind of psychic. And it is the same with books of the Bible containing prophecy.
If Revelation is a book of prophecy (a title it claims for itself), then the purpose of the Book of Revelation is NOT to predict the future, but to make God's truth known.