I began pondering about the reasons why this new light was made and have come to a few theories that may be plausible. My conclusion is that the Society is hell bent on eliminating the discrepancies to their authority.
The Ancient Lineage of the Faithful and Discreet Slave - Eliminated
The Watchtower Society's claim that a Faithful & Discreet Slave Class has always existed throughout history since Pentecost 33 CE has been quite a burden for them to prove historically. The reason why it’s so damning begins with their publications which detail the organization’s history, i.e. “Jehovah’s Witnesses: Proclaimers of God’s Kingdom”. The book (along with several other publications) stressed that Charles Taze Russell began his study of the bible independently and privately without sectarian bias, which allowed him to revive the great spiritual truths that had been long lost. However, the FDS doctrine required all JW’s to believe that an unbroken slave class channel had always existed, feeding each succeeding generation.
Why I think it was eliminated.
Upon critical examination of both the doctrine and the WT’s history, we find that they contradict each other. If there was a 1900 year old slave class, why didn’t Russell and his associates feel they could go to it or receive the great spiritual food which the passage of the centuries should have brought? Why did Russell have to study the bible independently and privately to revive these great truths if the FDS existed prior to Russell’s time? Obviously, this particular aspect of the doctrine didn’t support Russell’s journey and historically the WTS could not prove an unbroken channel of true Christianity over the centuries. So the governing body eliminated it and moved the birth of the FDS to 1919.
We Were Cleansed in 1919 - Eliminated
This new light where the FDS is still progressively being cleansed is well thought out. It helps defend many of the criticisms which show their continued babylonish practices during and after their supposed cleansing in 1919. It also gives them better immunity among the R&F when/if they crap the bed with current interpretations, predictions, or negative PR moments.
Why I think it was eliminated.
This new teaching takes away some core arguments made against their authority during the years. If you go back and review the food and faith that Jesus approved of during the judgment window of 1918-1919, you will find that the Bible Students were in absolute biblical darkness. Their ridiculous interpretations of the bible along with preaching a nationwide gospel of false prophecy until 1925 are detrimental to their authority. The reasons for their appointment is clearly evidenced in the publication titled: God’s Kingdom of a Thousand Years Has Approached!” (Page 350)
“The serving of food, the right sort of food, at the proper time was the issue. It had to be according to this that a decision must be rendered by the returned master. –Not only was the regularity in serving the spiritual food a problem, but the quality of the food itself was to be considered. In this respect the body of hated, persecuted Christians, who always sought to be faithful slaves of Jesus Christ, met the test.”
Any JW who reads, The Finished Mystery, Rutherford’s principle talk and printed book, “Millions Now Living will Never Die!”, or Russell’s volumes of "Studies in the Scriptures” would wonder why Christ would have picked out this admittedly error plagued source of information as THE example of faithfulness and wisdom, as the only ones passing the test and choosing them as the sole channel to send guidance to all mankind. Because many (including myself) have left the organization when conducting the very same inspection Jesus made, the Society has buckled down and shored up the doctrine by eliminating their “cleansed” status and making it indefinite.
They can disregard the arguments made about their hypocritical unclean practices during and after 1919. They now can easily dismiss all the evidence against their appointment by hypothetically saying….
”Look Brother Apostate, new light shows that we have always been in a progressive cleansing, so never mind all that false prophecy or false authority talk during our 1919 inspection! Jesus still loves us! By the power invested in me from the teachings of the great Pyramid of Giza and the 1925 false prophecy, I hereby disfellowship you for apostasy.”