...Ceryainly a circuit overseer would know the names so why not the organisation.
They could know if they wanted to, but they don't, possibly because it's an embarrassment to the Society. Since we are 'so deep into the last days of this old system' the number of partakers should be going down, not up. The only explanation offered for this is that some partakers are either being inflluenced by their previous religious beliefs, or they are mentally or emotionally imbalanced, and are mistaken that they are of the anointed.
This sounds more like a rationalization to prop up a broken belief system than an a proper explanation. Keeping track of the partakers wouldn't mean much if no one knows for sure who is really of the anointed, and who is mistaken.
At one time Witnesses said it was easy to know if you had the heavenly calling, that is was as clear as knowing if you were a man or a woman. How could anyone be confused about that? The increased numbers of partakers seems to show that it's either not so simple to know, or the whole doctrinal teaching of the 144,000 is wrong.
What is the Society's way of dealing with this problem? Simply saying 'we have no reason to keep a list of the anointed.'