The WTBTS doesn't want to admit they are wrong all at once. What could they say to those who've lost family members to the blood issue? So they do it very gradually, hoping the rank and file will not get suspicious.
They don't want to admit their meeting schedule, study burden, field service burden and convention burden has ruined health, physical and mental. They don't want to admit to their flock that JW's have died needlessly. They don't want to admit that they've broken up marriages and ruined childhood, careers, retirement and finances for millions of individuals, couples and families.
They imagine lawsuits and rioting villagers with pitchforks, torches and nooses (shotguns?), outside their Bethel headquarters.
Well hey, it's possible ain't it?