The anointed vs great crowd (JWs other sheep) JW teaching seems to be a result from the assertion that there will be a future paradise on Earth. Therefore, someone has to inhabit it.
The people who inhabit the Millenium Reighn on earth are survivors of the Great Tribulation.
1. They are not church-age Christians because they are all raptured to heaven by this time
2. They are not tribulation saints because most if not all will have been martyred during the GT.
3. Doing the math in Revelation; It looks like around 2/3 of the worlds population will have been killed during the reign of the Anti-Christ.
4. So, there will still be billions of people after the GT who are sorta standing around wondering what happened. It is at this point that Jesus assumes the throne in Jerusalem and commences with the "Judgment of the Nations" . The Watchtower calls this the Judgment of the sheep and the goats. Some are let in and some are not, based on their treatment of the Jews during the GT.
Mt. 25 - When the Son of man shall come in his glory, and all the holy angels with him, then shall he sit upon the throne of his glory:
32 And before him shall be gathered all nations: and he shall separate them one from another, as a shepherd divideth his sheep from the goats:
33 And he shall set the sheep on his right hand, but the goats on the left.
34 Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
35 For I was an hungred, and ye gave me meat: I was thirsty, and ye gave me drink: I was a stranger, and ye took me in:
36 Naked, and ye clothed me: I was sick, and ye visited me: I was in prison, and ye came unto me.
37 Then shall the righteous answer him, saying, Lord, when saw we thee an hungred, and fed thee? or thirsty, and gave thee drink?
38 When saw we thee a stranger, and took thee in? or naked, and clothed thee?
39 Or when saw we thee sick, or in prison, and came unto thee?
40 And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
42 For I was an hungred, and ye gave me no meat: I was thirsty, and ye gave me no drink:
43 I was a stranger, and ye took me not in: naked, and ye clothed me not: sick, and in prison, and ye visited me not.
44 Then shall they also answer him, saying, Lord, when saw we thee an hungred, or athirst, or a stranger, or naked, or sick, or in prison, and did not minister unto thee?
45 Then shall he answer them, saying, Verily I say unto you, Inasmuch as ye did it not to one of the least of these, ye did it not to me.
46 And these shall go away into everlasting punishment: but the righteous into life eternal.
The WT teaches that current JW members are in the group of people who will survive Armageddon. (Remember they backed up Christ's return to 19144) They also deny the rapture. Then they try to confuse the issue by claiming that modern Christians don't need to be part of the New Covenant "for the forgiveness of sins" (See Mt. 26: 27-28)
And this is what it is all about. It is an excuse to reject the NC every Lord's Supper so that JW's CANNOT be saved by virture of Christ's blood.... which is the offer on the table for church-age believers.