Why go to the trouble of reducing the strongest channeler in strength - through some convoluted and as yet unknown means - if she still ends up being stronger than all remaining channelers? What's the point of the strength reduction from a plot perspective if it doesn't change her position compared to other channelers?

Surely the point of reducing her strength is to bring her down to a level of humility or vulnerability where she cannot use her superior strength as her automatic advantage over everyone else.

In my view, the only purpose of reducing Lanfear in strength would be to make her weaker than some of the other female Forsaken. Else it serves no purpose.