Why would God permit people to destroy the credibility of the Bible with patently ridiculous nonsense?

(Revelation 22:18-19) . . .“I am bearing witness to everyone that hears the words of the prophecy of this scroll: If anyone makes an addition to these things, God will add to him the plagues that are written in this scroll; 19 and if anyone takes anything away from the words of the scroll of this prophecy, God will take his portion away from the trees of life and out of the holy city, things which are written about in this scroll.