Originally Posted by
FlyingStone
Because in normal and large majority of abnormal situations there is no requirement for trimming in the opposite direction of control column, as this would just cause the out-of-trim condition, that could lead to aircraft being uncontrollable. There is an override switch available on the aft pedestal that disables this feature, if situation requires it.
That isn't what the post was referring to, it is referring to the manual trim being too weak to overcome aero forces (and therefore "locked"
both ways) unless the pilot releases the control column (as per the later bit of the para regarding the rollercoaster). The trim wheel was made smaller, hence less powerful, on the NG.