Let's face it, dubs - in general, are a lazy lot. They don't study the deeper things. Hell, they don't even read the Watchtower from cover to cover.
There may be a few, here and there, that fancy themselves as researchers, but all they do is research WT publications and accept whatever the WTS hands down. The rest of em, as many of us were a part of, just did enough to get by. Half ass studied the WT study article the night before, or even the morning of, if at all. Never studied all the material for the Ministry School or Service Meeting. Our favorite meeting was the public talk. No prepping. Just sit there and pretend to listen. Never prepped for field service. You'd flip through the pages of the mags on the way to the territory.
If the WTS changes a doctrine and introduces it with little to or no fanfare, it's only a matter of time before everyone is re-indoctrinated with the new light, never realizing the change was made right under their noses.
You'd think that a change as significant as this would create a little bit of buzz, but after a year or two, most dubs will be spouting the new doctrine as of it was this way since the days of Russell.
If over-lapping generations didn't jolt em awake, which affects more of them personally, this change, not affecting the vast majoritie's status or position, won't do nuthin'