In the mists of time I seem to recall it was to do with Grip Seals and extra flexing allowed oil to seep out; then when oil changed to grease the restriction didn't apply. But could be wrong.
Do remember flying BO105 with the old and learned who designed the magnificent rotor system and being told not to use full pedal to slow Nr as they had never done the stress sums for it.
Guess we'll always find something to do the designers never thought of!