Did you read it? The point was/is that the nations serving Babylon is not based on them having do be destroyed or its residents having to be carted off to the location of Babylon. The nations serving was a result of recognizing that Babylon was the new world power and had authority over them. They became that 3rd world power with the battle in Haran when they overthrew once and for all Assyria (the then ruling 2nd world power)and that happen in 609.
Tell me something in your own words...you can clearly read that the WTS states that:
[Isaiah’s Prophecy 1 p. 253-254 par. 21 – He says: “These nations will have to serve the king of Babylon seventy years.” (Jeremiah 25:8-17, 22, 27) True, the island-city of Tyre is not subject to Babylon for a full 70 years, since the Babylonian Empire falls in 539 B.C.E. Evidently, the 70 years represents the period of Babylonia’s greatest domination—when the Babylonian royal dynasty boasts of having lifted its throne even above “the stars of God.” (Isaiah 14:13) Different nations come under that domination at different times. But at the end of 70 years, that domination will crumble.]
So tell me, since the 70 years mentioned in verse 11 and 12 is said to represent Babylon's greatest domination period and that period is said to have ended in 539, which logically means it started in 609, tell me, why does the WTS say that Jehovah called Babylon to account in 539 and Jehovah says that he would do so when 70 years have been fulfilled and yet you refuse to accept that the 70 years ended in 539?
[Jeremiah 25:11 And all this land must become a devastated place, an object of astonishment, and these nations will have to serve the king of Babylon seventy years.”’12 “‘And it must occur that when seventy years have been fulfilled I shall call to account against the king of Babylon and against that nation,’ is the utterance of Jehovah,]
[8-1-81 WT p. 27-28 - “The idol-worshiping Babylonians now were in line for
God’s judgment to be executed upon them. That happened in 539 B.C.E. when
Babylon was overthrown by the Medes and the Persians.”]