Why is the symbolic Euphrates dried up?

"Why do the waters dry up?
It says the waters were dried up to prepare the way for the kings from the east. (And the sixth angel poured out his vial upon the great

river Euphrates; and the water thereof was dried up, that the way of the kings of the east might be prepared.)
The kings from the east described in Revelation 19 where Jesus comes as a warrior sitting on a white horse and the armies of heaven are coming with Him to deliver His people from the death decree.
From the east, the way is prepared for them by the drying up of the Euphrates, by the fact that the multitudes take away their support from the Babylonian harlot." 

Stephen Bohr