In theory all anointed were part of the faithful slave. But in practice only the GB had the authority of the faithful slave. Everyone kind of realised that anyway.
Everyone, except the especially delusional JWs probably realised it... aka the anointed.
While you explained the old doctrine in a few sentences, it would take the GB at least one entire WT article with scriptures referenced in poor context, convoluted reasoning and crazy assumptions to explain the same thing.... I think they do this on purpose, it comes across as intelligent and thoroughly researched to the brainwashed masses.
The JW theology is a mess and it’s getting exponentially worse as time passes.