because it made sense to the people at the time
But the Bible writers did not write their thoughts according to the premise that the Bible is inspired so they didn’t have to understand what they wrote or could have been mistaken about what they intended to mean. So, in-spite of their beliefs at the time as to the identity of Babylon the Great juxtaposition the mistaken beliefs about the significance of the “disgusting thing that causes desolation” which Jesus clarified later on, the prophetic identity of Babylon the Great may not be Rome. And of course, there is an argument explaining that.